Okay, I went from 2.5" offroad H (loud) to 2.5" Mac offroad X (quiet compared to H) to 2.5" Dr Gas X (A little quieter because of how smooth it is) Go to mustangexhaust.com. They have a clip there with that exact setup.
You will like the sound. The x-pipe will always be quieter than the h-pipe. It will be a real smooth nascar-indy car sound. Like previosuly mentioned, go to Mustang Exhaust.
i got bbk long tube headers with dr.gas 3'' x pipe off road an debating on the mac cat back or two chamber flows.. cant decide.. does anyone know if those two have a similar sound ? which one will sound better..