i want to keep my mustang fairly quiet, i am going to run 3 inch exhaust with cats and plan on big hp numbers. Many mufflers are made for 3 inch piping for all the turbo cars and the like but which ones actually do their job. Do borla hush's keep the noise down?? What could i do?? Any suggestions?[edit, i found an artical in 5.0 that listed the decibals of different mufflers for high output 5.0's and the borla xs was the quietest of that bunch, just thought i'd throw in my own answer]