GMC Sierra For sale cat back for Sierra, original Fox muffler, Skyline. 3 inches, no back pressure at all. Goes 140 without getting choked or damaged. Custom made for the exit and the exit is original. Custom made by Ben Mardah and the kit is a full 3 inches. Its sound is quiet and its tone is nice, and if you close it, it makes no sound. Note: It was used minimally and without a device, and I don't have a sound for it.