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Discussion Starter · #1 · (Edited)
So this was an unpleasant surprise... I just got my JBA titanium ceramic shorties & high flow cats installed last week, and I went to the dragstrip today in excitement. Unfortunately due to weather, they weren't running the 1/4 mile runs, and only had the 1/8 mile runs instead (weird since its the same track and it was dry past the 1/8 mile mark but w/e).

After doing a few runs, I felt I was doing ok, but then I checked a picture of my slip from April when I set my all time record of 13.456 s @102.86 mph, and noticed that on that run my 1/8 mile was better.

My top 3 runs today were:

8.828 s @ 79.09 mph
8.907 s @ 80.41 mph
8.943 @ 80.42 mph

Without any reference that may seem nice and all, but on my April run mentioned above I had 8.633 s @ 82.01 mph

Essentially, roughly 0.3 s & 2 mph faster than with Shorties & High Flow Cats ... how does that make any sense? Shouldn't the shorties and cats improve exhuast flow and give you about 20 hp / tq? (that's what it said on the JBA website, roughly 5 from the pipes and 15 from the headers).

I did also install a front & rear strut bar on the car, but that couldn't have added so much weight as to counteract the benefits of headers & then some...

Could it be that my 1/8 mile time is worse, but had they recorded my 1/4 mile time it would have been better because headers reduce low end torque / hp but increase it higher up, thus changing you power curve??? I just want to make sense of this because based on all the crap I went through to get these parts & have them installed, and the amount of money I spent on them, it really upsets me to have a worse time than before...

Before doing that April run, I did change my tranny fluid, and it felt amazing, like a new tranny. Since then it has gotten a bit sluggish again, so could that be it? My 0-60 times are worse tooo... i was getting low 5's and high 4's, best was 4.76, now its high 5's and low 6's...
 

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My experience is lower back pressure, means less hp/tq down low and more up top.
I don't enough about drag racing to back this up, but what about the weather? I always hear on the tube about heavier air and so forth affecting run times.

Just thoughts, but I totally understand the frustration
 

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Discussion Starter · #3 ·
Weather was roughly the same today as it was in April (cold & windy), however today the track was a tad moist due to rain yesterday (but I have AWD so slippage wasn't really an issue)
 

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If the Density Altitude was similar then you may be able to compare.

Typically moving the torque curve upward hurts acceleration at lower speeds as the HP/TQ are further up the rev range. Without tuning to match your new exhaust you may be experiencing this...
 

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Discussion Starter · #5 ·
So you think a tune would solve the problem? I'm already running DS 93 Octane CAi Tune, which I also ran in April, but I guess you mean a custom Dyno Tune. There is a local dyno shop that has an AWD dyno, I'll give them a shout and see what they can do. The cost is 250 per hour, though I don't know how much a tune would be.
 
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