I have a 94 camaro z28 stock lt1 auto tranny what is the best type of header as far ss ease to install it has a 3 inch cat back already to a flow master 1 in 2 out. So if I could find something that uses the cat back I have already would be great or atleast would weld I to it easy also can you not do actual duals on these?
There's a large number of people here running Pacesetter long tubes. I don't have them and don't know the details, but they might be a good possibility. Hopefully someone with the Pacesetters will be able to tell you if they will mate up with your catback, and how easy the install and plug access is.
You can run duals. Several ways to do it. Mine are just Borla XR1 mufflers bolted to the collectors and 3" pipes with turndowns in front of the axle. Others have managed to do an X-pipe setup with two pipes over the rear axle. There is a BMR panhard rod relocation kit that helps with that. I think some of these are in a thread "stickied" on the "Exhaust Systems" forum.
I can not answer you question totally as I have Pacesetter LT's mating to a Corsa cat-back. However here is a picture of where the Pacesetter Y-Pipe ends. I used a short 3" (Advanced Auto) extension to mate the Y to my cat-back. You may have to fabricated something similiar..