so i found this dude selling x-pipe true dual before the axel dumps for camaro or trans am. 98-2002 for long tube headers. buts says you can modify stock exhaust manifolds to fit on your exhaust.

just wondering how would i modify the stock manifold/cats to use this exhaust system,

 

Take the car and exhaust set up to a muffler shop and they should be able to make it work. Honestly though, I would save up and have some LT's put on at the same time.