Mine sounded close to stock decibels on the inside and loved it. This was with Long Tubes >> 3" single Y with no cats >> dumped after the axle. Ran it for a almost 3 years before going with duals.
Video taken a few hours after install in 2010
Taken Jan' this year. Couple of weeks later is when i went to the much more head pounding Dynomax 3" DI/DO Ultra Flow X.