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Discussion Starter #1
Hello everyone,
I’m looking to do some mods this winter and I have a 2005 300c 5.7 rwd and its stock besides the cold air intake and 2 cherry bomb vortex mufflers with no resonators. I’m wanting to make it faster I’m not looking to run at a track, or anything just add more HP and speed. I’ve slightly looked through this site and its really outdated so not sure what’s still available since it’s 2020.This is my first 5.7 hemi and don’t know what to order or where to start any help would be appreciated.
 

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Discussion Starter #3
Thanks for the quick reply and i looked on their website and there are 4 different models for my year what would be the best one to purchase? Predator 2 (custom tuning), Intune l3 (custom Tuning), Intunel3 (50 state legal) and Predator 2.
 

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Discussion Starter #4
Thanks for the quick reply and i looked on their website and there are 4 different models for my year what would be the best one to purchase? Predator 2 (custom tuning), Intune l3 (custom Tuning), Intunel3 (50 state legal) and Predator 2.
 

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A steeper rear end gearset / Getrag LSD will do wonders and likely be the most effective mod short of a supercharger.

I started with a 3.55 and then jumped to a 3.91 and I enjoy every second of it.

Sent from my SM-G950U using Tapatalk
 

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Thanks for the quick reply and i looked on their website and there are 4 different models for my year what would be the best one to purchase? Predator 2 (custom tuning), Intune l3 (custom Tuning), Intunel3 (50 state legal) and Predator 2.
Which ever you can afford, if you would like a custom tune get one that has CMR capabilities. You should probably contact them and they can answer your questions regarding the differences.
 

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All true above. First, what is your budget? Second, how much power and how much faster do you want? Are you just interested in performance, fuel economy, or both. On both my 5.7 Hemi's (05 Magnum and 06 Jeep Grand Cherokee) I've spent almost 10 years, a little at a time so as not to upset the wife, doing mods in what I considered a logical order. Definitely start with a tuner and, if you desire a custom tune. I've never done that with mine, but I have all the tuners for both....Superchips, Diablosport and HPTuner and I have a pretty good handle on what needs to be done tune wise.

Since yours is an 05, I am sure you're aware of the dropped valve seat problem with the early Hemi's. If you're not familiar with it, do an internet search on, "early Hemi dropped valve seats" and you'll see what it is all about. IMO, the next thing you should do it insure the cooling system is in top notch condition.....a cooler thermostat (I run 190* ones) and, with your tuner, reset the cooling fan start temperatures to lower settings. Here's what I use on all 3 of my Hemi's: Low: 200*; Medium: 205*' High 210*. Also make sure you use nothing but the factory recommended HOAT type anti-freeze mixed 50-50 with DISTILLED water. Not necessary, but I also use a lower pressure cap, about a 15 pound one. This takes a little of the load off the cooling system, especially the cheapo radiators. Set up this way, I've never seen any of mine past about 215*, even in 105* temperatures and idling for long periods of time. Also, be aware that this IS NOT a cure all, but it may prevent a drop, since most happen with an overheat or excessive heat soak condition. A typical scenario is you stop for gas (5-15 minutes) and then when you try to re-start it, it either won't start or it starts, runs very rough, makes a lot of engine noise and/or stalls. The more you try to start it, the more damage you do to the engine. Repair prices run from $1500-10000, depending on damage and extent of rebuild desired.

I've been running the cooling setup above for many years and reworking the heads on both of the 5.7's was the last thing I did. I finally pulled both apart and had all new valve seats installed, ported and polished (doesn't help that much) and .030 in. milled off them to raise the compression ratio to about 10.2:1. On Maggie, when the machinist was cutting out the intake seats (the ones that fail the most), he said one started spinning in its bore when it was only about half cut out. All the others had to be completely machined out. He said that the one that spur could have been a candidate for a drop......no way of knowing though.

Back to the mods.... the LX Hemi's log manifolds are not all that bad, so doing the whole thing isn't necessary right away. When you do, the best way to go is long tube headers and a good straight through cat. back exhaust. I have JBA Shorties on Maggie and ARH Long Tubes on the Jeep. My Chrysler 300 SRT exhaust is completely stock and works fine for me. Other less expensive stuff that helps is listed in my signature in the approximate order I did them. For both of my 5.7's, I've gained about 120-130 hp. and my fuel economy is now about 25% better than stock......Maggie, 27-30 mpg, Jeep, 20-23 mpg. Oh, not listed is I do have a Getrag 3.06 LS Differential in Maggie, as it is mostly our highway cruiser.

Good luck and happy modding. Keep us posted on your progress.
 

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Discussion Starter #8
I'm interested in performance and fuel economy. My budget i'd say anywhere from 1500-2000. I'm glad you mentioned the radiator and cooling part because i just had to replace it due to a small crack in it and bought a new thermostat but not a 180* etc. I would love to do a valve seat and head upgrade but that would be later in the future. I purchased the car used but in very good condition and it had 174k and now has 189k (daily driver) so not looking to keep the car to long due to miles and wear and tear but i'd like to keep it till the wheels fall off so don't want to dump a ton of money on like cam, headers etc ( only if needed) just small things if possible. My first purchases will be a tuner and then another thermostat but anything else reasonable in price far as bolt on things I'm willing to purchase.
 

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IMO, if you don't plan on keeping the vehicle very long and your not budgeting too much for mods., I'd probably stick with less expensive things that will give you a little better performance and, hopefully fuel economy. I think, if it were me, the first few orders of businees would be, in this order, a cooler thermostat, a tuner that will allow you to reset cooling fan temps., perhaps an underdrive crank pulley, a catch can, and some sort of straight through (no switchbacks) muffler. For the thermostat I'd use a 180* if your in a warmer climate or a 190* if your in a cooler climate. Next with the tuner, first set the fan start temps. and then, if you're not going to get a custom tune, I'd experiment and find out which canned tune provides you with the best performance and fuel economy, taking into consideration the price of a good top tier fuel and price/availability of it in your area. Next, I'd probably do either the underdrive crank pulley or the catch can. The catch can won't necessarily give you much performance/fuel economy, but it helps keep oil and condensation out of the intake, combustion and exhaust tracts which may allow the PCM to add a little more timings. (While you're at this one, change the PCV Valve unless you know it's been recently changed. Finally, eliminate some of the exhaust restriction with a good straight through muffler. The stock "suitcase" that comes with the vehicle is quite restrictive. Doing these things could give you as much as about 50 more hp. and maybe a couple more miles per gallon. If you're able to do all this work yourself and not have to pay labor for everything, next I'd consider a cam. The parts.....cam, valve springs, push rods, etc. cost less than $1000....the labor to have it done is what would kill you. A mild high lift, longer duration cam can give you anywhere from 30-50 hp. depending mostly on your tune and your exhaust system.

Here's a couple references that'll show you what I mean. Disregard the bigger heads and note the difference just a cam and headers make:

This one will enlighten you on the benefits of a catch can. It was posted on an SRT Hemi forum by Mike at Diablosport, the tuner maker:
"No, this is where I comment on lost power due to oil contamination in the intake tract/combustion chamber. I will assure you that after having seen as many logs of as many HEMIs as we have here at DiabloSport, not to mention the numerous HEMI vehicles we have had on our dyno for R&D, I can say, without a doubt, that the HEMI's PCV/Oil Vapor control is the worst of anything we deal with. All you have to do is pull your intake manifold to see the puddles of oil collected in there, and realize that it eventually gets in the combustion chamber, and oil don't like to burn, thus, detonation occurs.

There is no gimmick here. HEMI's have KR issues. The KR issues are 99% of the time contributed to by oil contamination in the intake charge, reducing the effective octane in the combustion chamber, and leading to a loss of performance.

Plenty of people have seen solid power gains on even stock vehicles when getting rid of an oil issue by adding a catch can that works properly.
https://www.cherokeesrt8.com/threads/catch-can-billet-tech-vs-diablosport.50350/post-690577
 
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A couple other things came to mind that may be of interest to you. Before you go dumping a bunch of $$$ into it, do a compression check and a cylinder leak down test. These two tests will tell you everything you'll need to know about the condition of the engine. You have a little more miles on yours, 189 K compared to 170K on my 06 300CSRT8. I bought it from my Grandson with a slight engine noise. After doing all the preliminary tests, I decided the overall condition of the engine was sound. After extensive troubleshooting (don't want to tear into it farther than need be), I pulled the heads and front cover.and ended up doing a cam, valve lifters, valve job with new valve springs, and an 85 mm throttle body. Cost of all this was about $2000, but I had a set of 6.1 valve springs and the 85mm throttle body laying around from the 5.7's. The SRT now has about 460 hp. and gets 12-14 mpg in town (depending on stop and go) and 22-25 mpg on the highway. I did not advance the cam in it like I did in both 5.7's, because it has plenty of low end power.....amazing what about 25 more cubic inches in the engine will do..

Another thing you could do, if you don't want to go with a new cam is advance the stock cam by one tooth on the cam gear. This will advance it by just under 7* and slightly move the power curve (hp/torque) to a little lower RPM. The stock cam is already pretty good on the low end, but this should make it even a little better. On my two 5.7's, (modded almost exactly the same) the Jeep, with the performance cam, is advanced a total of 6* and Maggie, with the same type of performance cam, is advanced a total of 10*. As far as performance goes, the Jeep is about 600-700 lbs. heavier, has 4 WD, has worse aerodynamics (even with the SRT body kit on it), but does have slightly better gearing in 1st and 2nd. For about the first 100 ft. it is quicker than Maggie and about the same as the SRT, but beyond that both Maggie and the SRT leave it in the dust. Oh how nice it would be to have a 410 cu. in. stroker in all of them.....see the Hot Rod Network article above.
 
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Discussion Starter #11
Thanks for the replies well said my friend. Looks like I'm going to start with the compression check and cylinder down leak test, cooler thermostat, pcv valve, oil catch can, diablo tuner and Under-drive crank pulley. I think i'll be fine with those mods and esp when i get the tuner and add a costume tune and see how she feels afterwards to see if i want to go forth with cam valve springs etc.


I can do most of all repairs and bolt ons my self so that would save me a ton of money my next question is when purchasing a oil catch can is there a certain one you prefer i buy there is so many out there. Also once i do a compression test and down leak test i'll post results and see where to go next.
 

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Thanks for the replies well said my friend. Looks like I'm going to start with the compression check and cylinder down leak test, cooler thermostat, pcv valve, oil catch can, diablo tuner and Under-drive crank pulley. I think i'll be fine with those mods and esp when i get the tuner and add a costume tune and see how she feels afterwards to see if i want to go forth with cam valve springs etc.


I can do most of all repairs and bolt ons my self so that would save me a ton of money my next question is when purchasing a oil catch can is there a certain one you prefer i buy there is so many out there. Also once i do a compression test and down leak test i'll post results and see where to go next.
FWIW, with the tuner, I'd start with just the "canned" tunes and see if one of them might be adequate for your needs. If not, then go with a custom tune. Bare in mind, there is not a lot they can legally do with the tunes.....mostly air/fuel mixtures and timing advance curves. They can't do anything that will change any of the emissions settings. You may have noticed that, when your engine is mostly cold, it runs noticeably better than when it warms up. This is mostly a result of a slightly richer fuel mixture when cold.....closer to what is needed for better performance. Once warmed up, at cruise (light throttle settings), it's running at about 14.7:1 A/F ratio. Best WOT power is achieved somewhere between 12.7-13.2:1. The O2 Sensors monitor/control the cruise mixture, and the PCM uses "pre-programmed" fuel tables when running at WOT. These are the tables that the tuners work with. The stock WOT A/F ratio is somewhere around 11.8-12.0:1.....a little on the rich side. I believe they do this to keep from running them too rich under heavy load, thereby (hopefully) extending the engine life.

If, at some point you want to go with the cam, it's not a real tough job and you can change the valve springs with the heads on which is a big time saver, unless you want to change the valve seats.. It does take a special tool though. I did both of my 5.7's that way, and in just last year or two pulled the heads on both and did the valve seats and other stuff. IMO, porting and polishing the stock heads with the stock displacement is not worth the $$$.....see Hot Rod Network article. Milling .030 in. off them to raise the compression slightly is probably just as effective. I'd guess, on my two 5.7's with the ported/polished heads and .030 in. milled off netted me maybe 25-30 hp. at best. Anyway, if you try this one, doing the cam job and changing the valve springs is about a full weekend's job.

You're right, there are a zillion different catch cans available out there, some good and some not so good, so, again, it's a matter of choice. Personally, all of mine have Billet Technology units on them.....about $100. They were one of the first ones to come out with them (I think they make the ones for Diablosport too) and have a pretty good reputation and definitely good quality.
 

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FWIW, with the tuner, I'd start with just the "canned" tunes and see if one of them might be adequate for your needs. If not, then go with a custom tune. Bare in mind, there is not a lot they can legally do with the tunes.....mostly air/fuel mixtures and timing advance curves. They can't do anything that will change any of the emissions settings. You may have noticed that, when your engine is mostly cold, it runs noticeably better than when it warms up. This is mostly a result of a slightly richer fuel mixture when cold.....closer to what is needed for better performance. Once warmed up, at cruise (light throttle settings), it's running at about 14.7:1 A/F ratio. Best WOT power is achieved somewhere between 12.7-13.2:1. The O2 Sensors monitor/control the cruise mixture, and the PCM uses "pre-programmed" fuel tables when running at WOT. These are the tables that the tuners work with. The stock WOT A/F ratio is somewhere around 11.8-12.0:1.....a little on the rich side. I believe they do this to keep from running them too lean under heavy load, thereby (hopefully) extending the engine life.

If, at some point you want to go with the cam, it's not a real tough job and you can change the valve springs with the heads on which is a big time saver, unless you want to change the valve seats.. It does take a special tool though. I did both of my 5.7's that way, and in just last year or two pulled the heads on both and did the valve seats and other stuff. IMO, porting and polishing the stock heads with the stock displacement is not worth the $$$.....see Hot Rod Network article. Milling .030 in. off them to raise the compression slightly is probably just as effective. I'd guess, on my two 5.7's with the ported/polished heads and .030 in. milled off netted me maybe 25-30 hp. at best. Anyway, if you try this one, doing the cam job and changing the valve springs is about a full weekend's job.

You're right, there are a zillion different catch cans available out there, some good and some not so good, so, again, it's a matter of choice. Personally, all of mine have Billet Technology units on them.....about $100. They were one of the first ones to come out with them (I think they make the ones for Diablosport too) and have a pretty good reputation and definitely good quality.
FWIW, with the tuner, I'd start with just the "canned" tunes and see if one of them might be adequate for your needs. If not, then go with a custom tune. Bare in mind, there is not a lot they can legally do with the tunes.....mostly air/fuel mixtures and timing advance curves. They can't do anything that will change any of the emissions settings. You may have noticed that, when your engine is mostly cold, it runs noticeably better than when it warms up. This is mostly a result of a slightly richer fuel mixture when cold.....closer to what is needed for better performance. Once warmed up, at cruise (light throttle settings), it's running at about 14.7:1 A/F ratio. Best WOT power is achieved somewhere between 12.7-13.2:1. The O2 Sensors monitor/control the cruise mixture, and the PCM uses "pre-programmed" fuel tables when running at WOT. These are the tables that the tuners work with. The stock WOT A/F ratio is somewhere around 11.8-12.0:1.....a little on the rich side. I believe they do this to keep from running them too rich under heavy load, thereby (hopefully) extending the engine life.

If, at some point you want to go with the cam, it's not a real tough job and you can change the valve springs with the heads on which is a big time saver, unless you want to change the valve seats.. It does take a special tool though. I did both of my 5.7's that way, and in just last year or two pulled the heads on both and did the valve seats and other stuff. IMO, porting and polishing the stock heads with the stock displacement is not worth the $$$.....see Hot Rod Network article. Milling .030 in. off them to raise the compression slightly is probably just as effective. I'd guess, on my two 5.7's with the ported/polished heads and .030 in. milled off netted me maybe 25-30 hp. at best. Anyway, if you try this one, doing the cam job and changing the valve springs is about a full weekend's job.

You're right, there are a zillion different catch cans available out there, some good and some not so good, so, again, it's a matter of choice. Personally, all of mine have Billet Technology units on them.....about $100. They were one of the first ones to come out with them (I think they make the ones for Diablosport too) and have a pretty good reputation and definitely good quality.
Sorry, I meant, "to keep from running them too LEAN under heavy load."
 

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I'm by no means an expert on this car or Hemis. I only stumbled into this thread while researching parts for my fathers Hemi.

Lower temp thermostats are almost always dumb. It will not make your engine run any cooler. What it will do is prevent it from reaching operating temperature as fast resulting in at best nothing, at worse and frequently increased engine wear.

The tighter final gear ratio probably won't make sense for a daily driver either. You'll be shifting more, and modulating the throttle more on the launch. Considering you'll be on the street with street tires this makes little sense. You're better off improving the power band. Once you get traction you'll see some benefits with the new gears until you reach a lower top speed. Those benefits could be had with horsepower while reducing the need to shift so much, modulate the throttle, and keeping your top speed.

A camshaft upgrade should provide a decent HP to money ratio and make the exhaust note sound even meaner. I wouldn't go full race cam but you could get something fairly aggressive and upgrade the valve train while you're there. Valves, springs, pushrods, and maybe lifters/rockers if necessary.

The tuner is a great idea either way and necessary for letting the computer run properly with most major upgrades.

If you have a lot of money to play with just get a complete set of built heads/valvetrain and twin turbo kit. You will see big gains with the turbo kit and if you keep your foot out of it you can even see a decent MPG increase.

If you don't go turbo get some good longtube headers and either way, true dual exhaust pipes with a crossover x or h pipe.

Do some research into what parts fail at what power level. At some point you'll need to beef up the bottom end, get ARP head studs and it's starting to get expensive. With the turbo you'll likely need to get some more fuel and possibly ignition upgrades depending on safe boost levels.

Cooling upgrades such as higher CFM fans, better radiator, oil cooler, and trans cooler would be a good idea if you start getting significant power increases and you drive it hard. Just keep the stock thermostat.

As someone who has never owned a HEMI, definitely get a cam, valves, valve springs, pushrods, full exhaust and tune. If you have the money heads and turbo but be prepared to start getting fuel, ignition possibly other things to support the pressures reliably.
 

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I'm by no means an expert on this car or Hemis. I only stumbled into this thread while researching parts for my fathers Hemi.

Lower temp thermostats are almost always dumb. It will not make your engine run any cooler. What it will do is prevent it from reaching operating temperature as fast resulting in at best nothing, at worse and frequently increased engine wear.

The tighter final gear ratio probably won't make sense for a daily driver either.
You'll be shifting more, and modulating the throttle more on the launch. Considering you'll be on the street with street tires this makes little sense. You're better off improving the power band. Once you get traction you'll see some benefits with the new gears until you reach a lower top speed. Those benefits could be had with horsepower while reducing the need to shift so much, modulate the throttle, and keeping your top speed.

A camshaft upgrade should provide a decent HP to money ratio and make the exhaust note sound even meaner. I wouldn't go full race cam but you could get something fairly aggressive and upgrade the valve train while you're there. Valves, springs, pushrods, and maybe lifters/rockers if necessary.

The tuner is a great idea either way and necessary for letting the computer run properly with most major upgrades.

If you have a lot of money to play with just get a complete set of built heads/valvetrain and twin turbo kit. You will see big gains with the turbo kit and if you keep your foot out of it you can even see a decent MPG increase.

If you don't go turbo get some good longtube headers and either way, true dual exhaust pipes with a crossover x or h pipe.

Do some research into what parts fail at what power level. At some point you'll need to beef up the bottom end, get ARP head studs and it's starting to get expensive. With the turbo you'll likely need to get some more fuel and possibly ignition upgrades depending on safe boost levels.

Cooling upgrades such as higher CFM fans, better radiator, oil cooler, and trans cooler would be a good idea if you start getting significant power increases and you drive it hard. Just keep the stock thermostat.

As someone who has never owned a HEMI, definitely get a cam, valves, valve springs, pushrods, full exhaust and tune. If you have the money heads and turbo but be prepared to start getting fuel, ignition possibly other things to support the pressures reliably.
Welcome to the forum. I'll agree with you on your first sentence. After messing with and "mildly" hopping up these things (Hemi's) for about 16 years, believe it or not I do have a little knowledge of what works and what doesn't. The OP for this thread has a very limited budget ($1500-2000), doesn't plan to keep the vehicle very long and plans to use his ride as a daily driver. His budget would not allow him to do very much at all, especially if he has to pay labor charges for any mods. he decides to do. Below I'll address some of your comments/assumptions as I am aware that they relate to his early (2005) Hemi.

A slightly lower temperature thermostat, WITH corresponding lower cooling fan start temperatures is an excellent idea on the early 5.7 Hemi's that have the potential to drop valve seats due, in part to Chrysler's improper intake valve seat to cylinder head press fit clearance. This is a real possibility (do an internet search on, "early Hemi dropped valve seat problem"), especially if the engine is overheated, and even if not overheated, but heavily heat soaked with a loose fitting intake valve seat. The stock thermostat is a 203* unit with cooling fan start temperatures beginning a little above 220*. Many of these issues occur after the vehicle is stopped for a short period of time (get gas, a quick stop at a convenience store, etc.) and then after it has heat soaked real well in this short time, a restart is attempted. Many times it'll either not start, start and run real rough, and/or make all kinds of horrendous noises. The more the driver tries to start it, the worse the damage becomes. Bottom line, a cooler thermostat in an early (2005-2007) is a good idea, as long as the cooling fan start temperatures are reset to match. A cooler thermostat DOES NOT make the engine heat up slower, it just opens at a cooler temperature.....warm up time is still the same.

I agree that a lower differential gear ratio, is pretty useless and a waste of $2000 plus unless you're going to go racing. These Hemi's have enough horsepower/torque, along with the NAG1 transmission gear ratiios and a relative high differential ratio, to more than adequately move these ~4300 lb. vehicles along at a pretty good clip. If one wanted to spend the money to change the differential, I'd recommend it only to get rid of the "peg leg" differential in favor of a limited slip unit. If this is done, going from a 2.82 ratio (stock Hemi RT's) to either a 3.06 (stock for 6.1 SRT8's), 3.23 or, at most 3.36 would be as low as I would go for a street vehicle. I'd also not go to the 3.23 or 3.36 ratio IF I kept the stock cam.

As far as cams go for daily drivers, again, it is counterproductive to install a cam that is too aggressive, as, among other things, it will adversely affect the vehicle's driveability, and cause a loss of low end power and fuel economy. The valve trains for the 5.7 and 6.1 engines are basically the same (rocker arms and valve lifters, except for MDS equipped vehicles) and completely capable of higher RPM (up to at least 6500 RPM) operation. The "completely stock" 5.7 RT WOT shift points are set at around 5800 RPM. Most milder cams, when coupled with 6.1 valve springs and pushrods work very well and deliver a pretty good power return for the $$$ spent......especially if you do the work yourself. The stock roller valve lifters (including the MDS ones) are more than adequate when used with most mild cams. Some folks opt to do away with MDS. Again, if not doing a lot of racing, it can be shut off in the PCM. For more aggressive cams and/or more race oriented, it's best to replace the MDS valve lifters in favor of 8 of the non-MDS type. Non-MDS valve lifters are the same for the 5.7's and the 6.1's.

For most folks, the cost of turbo charging is beyond cost limits and the chassis fit is nearly prohibitive. One wouldn't want to use any type of forced induction with boost higher than about 7 PSI, or large shots (much above a 100 shot) of Nitrous Oxide, with a stock rotating assembly. While the crank and rods can handle it quite well, the pistons would be the weak spot because the upper ring lands are too close to the top of the pistons and this is the weakest spot. There are quite a few supercharger kits available for the 5.7/6.1 engines that run from about $4000-8000.

Bigger cylinder heads (ported/polished/big valves), for the most part won't yield much gains, especially on a mostly stock early 5.7 engine and exhaust system. See "Hemi Head Test--Mild and Wild" in my post No. 9 above. Basically, the stock heads are more than adequate for the displacement and most mild modifications.

Exhaust systems for the stock 5.7 RT's are not all that bad, with the weakest area being the log type exhaust manifolds. All of the LX's come stock with duals and an X pipe.The stock logs vs. a four primary to one collector "shorty" header will only yield about 10-20 hp at best. Long tube headers and a good cat. back exhaust system yields a fair amount more power, especially if it is coupled with a better cam and kit, tune and cold air kit. Better Volumetric Efficiency (VE) equals more power. With the stock 5.7 displacement, retaining the stock size (2.25 in.) exhaust tubing is best. A cat. back with tubing that is too large for the engine displacement and its supporting mods can cause a loss of power instead of a gain. The stock SRT8 exhaust system, when used with a mostly stock 6.1 engine is, IMO, more than adequate in its stock form.

With the correct mods.and tune, it's easily possible for the 5.7 Hemi in the LX chassis, to deliver about 15-17 mpg in town and up to about 30 mpg on the highway......as long as the speed is kept below about 70 mph. The sweet spot for the stock, stock Hemi LX is around 63-67 mph, if one is trying to get the best fuel economy. Be sure to use a top tier fuel, preferably one that has not been reformulated......E85, Ethanol, Oxygenated, etc.

The bottom, bottom line is that the early LX chassis with the 5.7 Hemi and NAG1 transmission is a pretty good (and fun) ride, especially if it is maintained properly and "hopefully" a few well selected mods. are applied.
 

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A steeper differential gear through a getrag lsd was one of the best mods I did, especially paired with larger cam to reduce the loss of lower rpm power to the ground.

The engine is running as a higher rpm therefore you are always in the powerband.
You can't up the power in the low rpm range if you are staying NA. If going FI, then it's a different story.

I had no traction issues once I ran 10" wide wheels with Michelin PS4s tires in 305/35/20.

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A steeper differential gear through a getrag lsd was one of the best mods I did, especially paired with larger cam to reduce the loss of lower rpm power to the ground.

The engine is running as a higher rpm therefore you are always in the powerband.
You can't up the power in the low rpm range if you are staying NA. If going FI, then it's a different story.

I had no traction issues once I ran 10" wide wheels with Michelin PS4s tires in 305/35/20.

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I'll agree with that 100%, but 3.9 is too low for me, as mine is my highway cruiser. For me a 3.23 or 3.36 would have been perfect but the 3.06 works just fine, At cruise, it now runs at very bottom of my power range. Another 300-400 RPM would be perfect. I also changed my up/down shift schedules so when I punch it at almost any speed, it'll drop down one, two or three gears to get into the power RPM range instantly. I've done this to both my 5.7 Magnum (highway cruiser) and my SRT8. Big difference with just the shift schedules..
 
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I'll agree with that 100%, but 3.9 is too low for me, as mine is my highway cruiser. For me a 3.23 or 3.36 would have been perfect but the 3.06 works just fine, At cruise, it now runs at very bottom of my power range. Another 300-400 RPM would be perfect. I also changed my up/down shift schedules so when I punch it at almost any speed, it'll drop down one, two or three gears to get into the power RPM range instantly. I've done this to both my 5.7 Magnum (highway cruiser) and my SRT8. Big difference with just the shift schedules..
Yeah the 3.91 had me in 3000rpm+ at 80mph. The 3.55 was a better compromise but I always wanted to try the 3.91 for the extra kick.

How did you adjust the shift schedules? I consulted with Aj/Hemituner when he did my 6800rpm tcm and he said he couldn't reliably mess with those.

For example if I was cruising at 60mph and initiated a kickdown, the transmission would send it into 3rd instead of second even though I would have had nearly 2000 rpm I could play with in 2nd.

It didnt like to arrive in a gear above 5000rpm. That's understandable for a stock setup but would have been nice for a modded one.

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Yeah the 3.91 had me in 3000rpm+ at 80mph. The 3.55 was a better compromise but I always wanted to try the 3.91 for the extra kick.

How did you adjust the shift schedules? I consulted with Aj/Hemituner when he did my 6800rpm tcm and he said he couldn't reliably mess with those.

For example if I was cruising at 60mph and initiated a kickdown, the transmission would send it into 3rd instead of second even though I would have had nearly 2000 rpm I could play with in 2nd.

It didnt like to arrive in a gear above 5000rpm. That's understandable for a stock setup but would have been nice for a modded one.
That's exactly why I modified the up/down shift schedules and torque management on all of mine. You're at a real disadvantage when you can't access a low enough gear on a WOT downshift.. My SRT was terrible (I am still makng minor tweaks to it as time allows), especially at the lower speeds.....maybe 50 mph and below when I should be able to access first gear but stock would only go down to 2nd. Do you have a Mopar Performance TCM in yours? If not, it's a big help and I'd highly recommend it. I have one for the SRT but am setting up the stock one the way I want it first and then I'll install the MPTCM and program it like the one I have in my 5.7 Magnum.

I use a combination of a modified Diablosport engine and transmission tune and an HP Tuner for setting up everything the way I want. It doesn't take much to get it in the ballpark, but a little longer to do the final tweaking to zero it in the way I want it. My procedure for the MPTCM is to first remove any tune (if you're using an all or in part handheld tuner) you have on the current TCM. I don't need to do that with the HP Tuner though because I have copies of all of my engine/transmission tune renditions for all 3 of my Hemi's. Upon initial installation, I make a copy of the MPTCM programming so I can go back to its stock setting if need be. Then I do the initial setup procedure that comes with the TCM which is fairly involved. Once that's done, I make another copy of the TCM programming. After that, I have at it with the HP Tuner, making changes, one or two at a time in relatively small increments, until I get it the way I want it. The HP Tuner uses transmission output speed to set everything up. I start with the upshifts first and get them the way I want them. Once that's done, I do the downshifts. The downshifts can be a little more difficult because you don't want to overlap up and down shifts. If possible, I like to set it up so a very slight application of throttle downshifts one gear, a little more throttle and it downshifts again, and at WOT it downshifts as far as engine RPM will allow. The first one I did was on my 5.7 Jeep with the 545RFE transmission and I have it set up perfectly. I could go in and tweak Maggie's settings a little more but it's not totally necessary. Like I said, when it install the MPTCM in the SRT and get the initial setup done, I just copy Maggie's setting over to it and go from there. It should be a lot easier than starting from scratch again.
 

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Nice, so HP Tuners is the key. I sold the car last week but yeah I had a Hemituner TCM that gave it NAG1 some amazing shifts.

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