Originally Posted by slik

I had a Rokktech Silent Might muffler installed about a year and a half ago, and it provides nearly the same as stock noise level. There is slightly more turbo whistle, but inside the cab of the truck you can't tell that I have a high performance muffler. These mufflers are designed specifically for the 6 cylinder Cummins and are tuned to have less back-pressure than a straight pipe between 1600 and 2800 rpm. The muffler has an absolutely straight through unobstructed flow path with four small ports near the rear that open into tuned chambers. They have a web site if you want more info.