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I was under the car this morning changing the oil and filter with mobil 1. While doing this, I thought I'd check out the other parts. I was surprised to see how restrictive the stock cast iron exhaust manifolds are, I realize it's a cost factor, but this is supposed to be a performance engine. I've seen more efficient looking stock manifolds on much cheaper cars. Each port does a 90 degree turn within 2'' or less into a restrictive main collector pipe which then dumps into the stainless exhaust system which is free flowing.
The exhaust manifold which is closest to the engine is usually the most important part of an exhaust system in creating HP.
I'm just surprised that they designed the rest of the system so well and used such restrictive manifolds. This is why the Dynatec headers do such a great job of improving hp and torque.
I think I'm trying to talk myself into buying a set!!!!
 

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FOAMAVEN said:
I was under the car this morning changing the oil and filter with mobil 1. While doing this, I thought I'd check out the other parts. I was surprised to see how restrictive the stock cast iron exhaust manifolds are, I realize it's a cost factor, but this is supposed to be a performance engine. I've seen more efficient looking stock manifolds on much cheaper cars. Each port does a 90 degree turn within 2'' or less into a restrictive main collector pipe which then dumps into the stainless exhaust system which is free flowing.
The exhaust manifold which is closest to the engine is usually the most important part of an exhaust system in creating HP.
I'm just surprised that they designed the rest of the system so well and used such restrictive manifolds. This is why the Dynatec headers do such a great job of improving hp and torque.
I think I'm trying to talk myself into buying a set!!!!
Yep, people swapping out for headers are getting awesome HP gains. Near SRT-8 numbers!!!
 

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Give an amatuer some advice if you would please. Whose headers? links? How much of a gain? documented #'s? Given the fact that most dealers ignore magnusson, what 'real' risk is involved with headers, cat backs, intakes, etc.?

Thanks for any time anyone could spare me with opinions or comments...
 

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Thank you!

Thanks for the info!
 

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CIA + Header = Gains

I have to endorse that the combination of a well designed cold air intake, and a header is currently the way to go with the Hemi. The issue with the engine check light coming on can be resolved by disabling the cat check.

Zilla
 

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goddardzilla said:
The issue with the engine check light coming on can be resolved by disabling the cat check.
Zilla
Do you have to get the dealer to disable the converter check? Other than the urge to drive the car like a maniac (great SIG BTW Zilla!) after going with intake/headers/catback, is there more than a minute threat of harming the 5.7, or the entire drive train, by squeezing out 50+ more HP?

For instance, I could trick out my '04 F-250 Turbo Diesel to the point that it'd smoke off all 4 tires to the rims, but I'm much more likely to ruin 5 stock driveshafts along the way. :eek:

So, any inherent danger in performance modding other than the way you drive her afterwards?

Thanks!!!
 

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StarJack said:
Do you have to get the dealer to disable the converter check? Other than the urge to drive the car like a maniac (great SIG BTW Zilla!) after going with intake/headers/catback, is there more than a minute threat of harming the 5.7, or the entire drive train, by squeezing out 50+ more HP?

For instance, I could trick out my '04 F-250 Turbo Diesel to the point that it'd smoke off all 4 tires to the rims, but I'm much more likely to ruin 5 stock driveshafts along the way. :eek:

So, any inherent danger in performance modding other than the way you drive her afterwards?

Thanks!!!
The information re disabling the cat check is from two sources one a header manufacturer, and two fro the Lap of America SRT8 - it had a CAI and Header and the computer cat check was disabled. How this was done I am not yet privy to, but will post as soon as I know.

Your are correct to look for weak points. The air/fuel mixture reported on the Dyno tests I have seen - if they have been accurately measured - seem fine.

The over the 300c the SRT8 has uprgraded drive shafts and diff. so that might be an area to examine - but as far as I am aware no-one has yet reported any problems with a 300c in this area.

The transmission is good for about 430ftlb of torque in factory 300c form so there should be enough margin there.

The cooling system appears adequate, as there are no multiple threads on overheating on the forum dealer problems section.

Warranty is another issue tho

Mechanically I see no problem with CAI and header unless it turns your driving style from Dr. Jekyll into Mr.Hyde - good question tho.

Zilla
 

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Got my Supermaxx headers installed today. No problems, excellent fit onto the car and with exhaust. No check engine light issues. Sounds and feels great. Now if Corsa gets their act on the road I will have a free breathing hemi machine.

No wonder it breathes better when you see the difference stock vs supermaxx:

 

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Hemi_mag, are you running these headers with the factory exhaust setup? If so did the cats come with the system still?
 

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FOAMAVEN said:
I was surprised to see how restrictive the stock cast iron exhaust manifolds are, I realize it's a cost factor, but this is supposed to be a performance engine. I've seen more efficient looking stock manifolds on much cheaper cars. Each port does a 90 degree turn within 2'' or less into a restrictive main collector pipe which then dumps into the stainless exhaust system which is free flowing.
Ha, this is Mopar tradition. You should see the old-style "log" manifolds they used on big blocks. Just be happy they make headers that fit...
 

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Dutch said:
Ha, this is Mopar tradition. You should see the old-style "log" manifolds they used on big blocks. Just be happy they make headers that fit...
Oooo...I think I've seen what you're talking about....and I thought the GM Ram horn style BB manifolds were bad. :eek:
 

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HaTaX said:
Hemi_mag, are you running these headers with the factory exhaust setup? If so did the cats come with the system still?
Yes I still have stock exhaust. Waiting for Corsa but may give up and go to Borla. Header kit fit into stock pipes without any issues. I bought the header exhaust system which header, high flow cats and extension tube to connect to standard system.
I dealt with TByrne Motorsports for both Volant and Supermaxx and very happy with price and delivery.
http://www.tbyrnemotorsports.com/300Ccatalog.html
 
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