First off, the exhaust bolts right up. There are hardly any differences between the two. The only thing I can find different is that the GT exhaust has a smaller resonator and some unidentified canister right behind it
. I suspect it's emissions-related. Now the muffler is much bigger than what I had on there before (a Midas muffler
) so I think I might be enjoying some free-flow benefits of a larger muffler. It doesn't sound any different though. What I really like is the look though. The look to me of the single larger exhaust tip out the bumper is MUCH more elegant and stylish than the two smaller ones. I'll get pics soon.
The biggest difference I can note is the STi hangers. They are VERY stiff, hardly flexible at all. This has good and (to some) bad implications however. The good part is the exhaust won't move!
In all honesty, ever since I've had the car, I heard a rattling noise in the back whenever I would go down a brick street. That sound is completely gone. But this stiffness also means that the movements of the exhaust are going to be transferred to the body. Upon startup, and whenever you change RPM's quickly, you can definitely hear and feel the resonance through the body. I think it's pretty cool myself 
, but some may be annoyed by it.Overall, I'm still extremely happy with the setup though. I got a much newer catback exhaust and new hangers for the price of the Midas muffler I had on it before
A worthwhile setup if you come across a deal like I did!
