pypes long tubes and x pipe..

benspeed has 2 good packages and you can get a tune to fit your set up from them and they are pretty dead on with tunes

BBK Mustang GT Long Tube Header, Mid Pipe, & Exhaust Package (05-10)

Pypes Mustang 1 5/8" Stainless Steel Long Tube Headers & X (05-10)

hope this is helpful

I would go with the bbk. I read that the pypes weren't tuned length and that they don't scavenge well. The BBK's were voted best bang for buck in either modular mustangs and fast ford's or 5.0 mag after a shootout with stainless works, kooks, dynamax, and some others. BBK's netted like 32 rwhp, this was a non-supercharged application where scavenging nets more hp. But the Pypes are cheap and probably would be decent since you are supercharged.

Check this link out-http://www.mustang50magazine.com/techarticles/m5lp_0904_s197_ford_mustang_headers/index.html

This is the article, the test car was supercharged. Good info here.