If you can afford a B&B Tri-Flo, those are good exhausts. I think they make one for 2+2s but I'm not sure. Greddy is also good. Pick one based on how it looks and how it sounds, those are going to end up being the most important factors to you.
www.bbtriflo.com (it wasn't working for me today but maybe it will for you)
You can also search on
www.twinturbo.net.