I know that the cat-back designs differ between the 93-95 cars and 96-97 cars (single cat Ys versus dual cat). My question is - if you replace the manifolds and factory y-pipe with headers and aftermarket y-pipe, which catback design are you supposed to go with to have everything fit without having to go to an exhaust shop?

This would be with Pacesetter LTs and their matching y-pipe, if that makes a difference.

Or do you have to take it in to an exhaust shop regardless to have the y-pipe mated to the catback, no matter which "version" of the catback you get?

 

The difference was the single cat, dual cat designs that differed in the 93-95 and 96-97 model years. The catbacks for the 93-95s had the extra s-shaped piece of piping that connected the y-pipe to the i-pipe. If you have the Pacesetter long tubes and y-pipe, it won't matter.