[Supraru]

Originally Posted by Porosallstar

with out knowing the details of your catback, i don't understand why anyone would say there's no gain??? ASSUMING of course that you're exhaust system is now larger than stock, ie. 3inch pipe from the cat and back, you're now having a more free flowing exhaust ergo you're gonna make more power, it might not be as much as a performance upgrade had you gone with like a 3inch turboback (catless), but you're still gonna get gains out of a catback exhaust system, more so if you get an aftermarket downpipe as well, and yes a tune will certainly smooth everything out and give you a nicer power band. however just like every single performance question, anything you ever do to your car, should be done with a set goal, in other words don't just by a catback, turboback, intake, turbo, intercooler or whatever other mod if you don't have a set goal of what you want your car to do, other wise you're pretty much wasting your time and money.

Because until you actually open up the whole exhaust you'll see no benefits. If you just put a catback on your exhaust is still running through two cats and a 2.5" pipe. By the time it gets to the midpipe portion whatever size it is it's not going to improve flow.