I have a Hahn and had a Borla 2.25" duel exhaust . I replaced it with a 3.00" and could see an immediate improvement . The turbo spools up faster and at higher rpm the boost doesn't fall back like it did with the Borla . Even with the stage 1 hahn the 2.25" Borla is a restriction and it does effect performance , especially above 4000 rpm .
As for the sound of the 2.50" being louder , the turbo tends to make the exhaust quieter , at least at cruising speed .
I would go with the 2.50" for sure . I'm not sure , but I don't think there would be much of a difference in sound between the two . The 2.50" may have a deeper sound .
Check out my album . There are some pictures of the Borla 2.25" system I took off , with some pictures of a VERY interesting restriction where the pipe enters the muffler . THAT RESTRICTION IS a problem and I understand the 2.50" doesn't have it .
Album ---
www.imagestation.com/album/?id=4292471319
Edited by - OC CRUZER on 09/20/2002 16:45:16