Longtubes and 3" y-pipe will be pretty low and with a lowered car will make it even tougher on tall curbs and speed bumps. If you added dual cats to try and keep it legal, it would lower clearance even more. If you're not looking to race the car, then some form of mid-length header would probably be your best bet. I would recommend ASM(Arizone Speed Marine) 3/4 length headers first and then one of the other brand mid-lengths like those Pacesetters or MACs or SLP even. Here's a picture of my old 96 SS with the coated Pacesetter longtubes with dual cats added to the y-pipe. The passenger side cat is no big deal with plenty of room. The driver's side is tough because of the floor brace you can see sticking down so I added the cat farther back in the y-pipe. It was tucked up about as good as you can get, but with a lowered car it would be a bad idea. ps - the front of the car is up on ramps in the picture so don't try to judge the ground clearance.
96 Camaro SS longtubes and dual cats
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