I've got both the compact wrap around pitts and the regular wrap around pitts. The bigger one makes the motor sound more like a DLE 30 - more deep and resonate tone and the compact sounds about the same as the stock muffler but takes 300rpm off the top end. I had to use the compact pitts in a World Models P-51 to clear the cowl and it worked well. I plane to try the Valley View wrap around Pitts next.