JUst got my RCS1.40 up and running again after it has been sitting around a while. I have always had a problem with what sounds like a miss in the engine, anyways first i tried the supersonic muffler in place of the previous pitts muffler, this was quite noisy and due to not wanting to disturb the neighbours to much i only run the engine for about 5 minutes, i noticed the miss was still apparent at top end.
Then using the exhaust stub that comes with the RCS, i managed to mount a super tigre 90 quite silencer onto the engine, once running this sounded a lot better, a lot easier on the ears and the miss was not apparent, does this make sense?

Lastly i am running a MAS 16x10 3 bladed prop, top RPM 6400 low stable is around 1900, it will go down to 1600 but fluctuates, is this in the ball park for this motor?