Al,

I was wondering I have a street tune by you and at the time you did it I had a highflow cat in it. I was wondering how badly I would mess the tune up by putting a test pipe in? Thanks for your help!!

Chris

 

Good question. How much does a change in exhaust really affect a tune after you've street tuned it? I'm torn between two exhaust systems and I was wonder if they would be interchangable (to some degree) without harming the tune too severly.

 

I don't think it will affect the tune. It might even free up hp cuz less restriction in the exhaust.
Al even sugg. to remove the taper on most cat-back exhaust to free another 5-8 hp. Also running race gas and turning up the boost some to acheive higher hp even after the tune.

 

So i should benefit from this in the long run. Also with a test pipe what does it actually do to your car compared to a test pipe.

Chris

 

huhh... Did you mean, how does a high flow cat compare to a test pipe. They say 7-10HP difference....

 

Although there is a significant perfomance gain from a staight test pipe - we have found that th tuning is not substantally effected as the maf sensor can read the additional ar flow and compensate accordingly

However - there may be some timing changes which could be made due to reduced back pressure

I would think it would be alright to go from a high flow cat TO a test pipe

However - going the other way may not be that god of an idea whih out doing some testing for possible detonation activity

 

thank you for your responses everyone!! I really appreciate it.

 

I have a Perrin test pipe on my car now. We have emission testing here so when it comes down to getting my car tested I'll have to put me stock cat back on. So this is gonna be a bad thing?

 

MY guess is that it would probably be ok unless you run WOT.