I think dynomax might be the only aftermarket vendor still offering a catback for the older GP's. Not really sure if it's availiable anymore though. I had a 1994 Cutlass Supreme and there was literally nothing. Ended up just having a custom setup done with a high-flow converter and full 2.5" pipe to a custom Y-Pipe and some stainless mufflers. It's not hard to make the 3.1 sound good in reality.