Ive got a catback off a 98GT and a H pipe of an 03GT and was wondering what will need to be done in order to put it on my 02V6 (stock exhaust currently).

 

Here in the off topic section is a post named new to dual exhust it will have the info your looking for

 

Sorry its here in the V-6 topics

 

The H-pipe will definately not directly fit your '02 without bending/re-shaping, as your manifold width atyour engine is different from that of the GT. I don't know about the fitment of the '98 GT catback on your '02; I know the '99-'04 GT exhaust will fit directlyto a aftermarket dual exhaust X- or H-pipe made for your car or to yourstock midpipe modified to eliminate the Y connection.

Here's a good link with general info on the subject:
http://www.miracerros.com/mustang/pipes.htm

 

Any 94-04 catbacks will fit on any 94-04 Stangs.