I've got a Bassani X-Pipe w/ High-Flow Cats & Bassani Cat-Back on my Mach 1 & it sounds awesome. I'll probably go w/ Kooks LT's & Kooks X-Pipe w/ a Bassani or Borla Cat-Back (haven't decided which yet) on my Cobra. I choose X-Pipe for the 5 extra RWHP!!!