On my 98 GT is my stock pipe setup 2 1/2 in/out of the muffler?</P>

 

i believe its 2 1/4. you don't want to go bigger than 2 1/2 especially out, or you will have clearance problems. at least that's my understanding, i have 2 1/2, and it's enough to affect wheel fitment on some aftermarket tires. and just looking at it, i wouldnt want to go bigger.

 

OK thanks alot!</P>