I do believe the Maxxfab uses a high flow cat as well. Backpressure is only a negative thing when refering to a turbocharged car since the turbocharger is it's own backpressure and therefore requires no additional backpressure. Normally aspirated cars need the backpressure in the exhaust to help keep up the exhaust gas velocity and to build RPM's faster.[sm=smiley2.gif]

 

so let me get this straight, a pipe that will flow the amount of air (cm2) that the turbo charger is pushing, would be no different then not having a pipe connected to the exhaust end of the turbo right?

 

That does seem to be sound. The same should also apply to the intake side as well. If you can get a free flowing exhaust that can flow the same rate as the turbo would be ideal, since the turbo is it's own backpressure.[sm=smiley2.gif]

 

see that makes complete sense to me. so why is everybody saying go with the 2.5" instead of the 3" if your not going to go over 350 hp.

 

Because it has been dyno proven that the 2.5" systems are just as good as the 3" systems up to that point. After that the 3" systems show their size advantage. If I could have afforded a 3" system as well as the Stage 2 with toys, I would have the 3". You also have to look at the intake side as well and what it can flow. The turbo outlet may be 3", but it is the CFM that it pushes that counts and also how many CFM the exhaust can flow in comparison to this.