Quote:
Originally Posted by ALMN
I thought there wouldn’t be any gains from an exhaust as well, especially catback system. I know the stock exhaust system has crushed pipes behind the xpipe and you would think its a restriction but i saw some testing on the internet and changing it to smooth diameter pipes didn’t show a power bump. Now the interesting thing is there are couple of independent third party dynos and reviews with Corsa catbacks with double x pipe coupled with a Rotofab dry intake no tune. They are showing gains around 20 whp on a stock tune. One guy claims almost 30 whp gain with the above combo plus bigger throttle body(He might have the secondary cats deleted though). I m not sure who to trust. It would be nice gaining 20 to 30 whp with stock tune and going back to full stock except catback for warranty work. Intake and throttle body replacement are pretty easy.
Forgot to add the finance part of things. Corsa catback with double x pipe (npp) is more than $3000 plus $400 for the Rotofab. Thats almost half of a supercharger money right there or a head/cam intake manifold package. So is the 20 or 30 whp worth it? If you are willing to throw away the warranty maybe not at that time but they can act as supporting mods in the future as well i think. Intake and good exhaust can support future mods when the time comes.
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Nobody is gaining 20-30 whp from a catback and/or cold air intake without a tune. The biggest restrictions on the factory exhaust system are the catalytic converters and the tiny diameter pipes that connect the stock exhaust manifolds to the primary catalytic converters. The crushed pipes before the muffler have zero effect on air flow. The factory catback has been tested to 900 hp without being a restriction.