3" MAC cat back
 

On a 90 GT, will the 3" MAC cat back bolt up to a stock 4 cat H-Pipe without modification?

uhhh dont know..but why would you want a 3 inch cat back if you still have stock h pipe ect ect...you most likely dont need 3 inch....im going to be running 3 inch exhaust but im also installing it along with a 410 cubic inch motor