Banks, Borla, and Pacesetter, all sell complete exhaust kits (I think) which include everything form the head back. That's a good place to start, however they tend to be pretty expensive.
All of these components can be bought piecemeal for cheaper as well, check eBay. If you want a good exhaust, get yourself some headers and a good muffler, and take it to a mnuffler shop to have them bend a new exhaust for you. I don't know what engine you have, so the diameter of the pipe is kinda up to you.