I have 04 GTO exhaust on mine. It's a 2-piece deal: middle with resonators, back piece basically extends the pipes to the bumper. They do not have the back muffler and the pipes and resonators are a little larger. Routing is similar for the middle section, but fitting after the cats has to be totally redone and pipes bent, welded etc., because they come at different angles and have different fittings. The back section has to be slightly bent to come out in stock location; which I still haven't done. If you have a good exhaust shop, it shouldn't be too difficult to make everything fit well
Good luck,
Aras