I bought this muffler as a resonator to minimize the "hum" I get at 1900-2100 rpm with my newly installed cat back exhaust system. The system was on a 2004 Dodge Ram 1500 with a Hemi engine. These engines are known from some "drones" with certain exhausts, mine wasn't that bad except in a very narrow range. In order not to be overly obtrusive, I chose this muffler based on the size and the fact that I would cut and fit the existing 3" exhaust pipe, then place the exhaust pipe on the muffler at a 90 degree angle and install two could clamp and done. Note that this piece has a 3" ID inlet and a 3" OD (shortened end) outlet. Very happy with the end result, the drone is completely gone but the exhaust still sounds deep and smooth.