Rusty, Paul Lamar tested the muffler and said it was loud (123 DB) but qualified that by saying he was standing right next to the engine in a metal building. He reported that others standing nearby found the sound to be mellow when compared to full race open exhaust systems. Not much good information to go on. The test was done at 6000 rpm but hp was not measured so we don't know how the exhaust affects performance. I was hoping for more and that led to my statement above about needing to get my engine running and on my own dyno. Jerry