It seems pretty good, not ungodly loud, not as much on top as an open silencer, but better bottom and mid. One thing, the supertrapp discs are stamped differently now. There's supposed to be .023" between the discs installed, ive got an .023 wire feed welder, and the wire will not fit between the newer discs. I had a stack of 3" discs from eons ago, .023" will fir between those, so im running the old discs. It wouldnt run right with the newer ones, too much back pressure, even with 16 discs. I'm working on another muffler, its a street bike can, it will be longer, with 4" supertrapp discs. Its round though, and i can't figure out how to keep it from invading on the tires space. Im a hammer mechanic, not an engineer.