This is an old perception from the days of screaming open piped engines. Current pattern aircraft still run tuned pipes on the 2 strokes and they are among the quietest aircraft you will find. If you have an open pipe (look at the Mac's Products site for the various pipe types - http://www.macspro.com/tunedpipes.asp ), then it will have a pretty sharp crackle to it. But a muffled tuned pipe is not at all loud. Second source of major noise is the propellor. The old pattern ships also screamed because of running medium pitch props at very high RPM (11x7 prop @ 15,000+rpm was typical) to generate speed. You can reduce much of that by running higher pitch props at lower rpm to get the speed. Also, APC props are much quieter than the older designs of the 70's and 80's, at any given rpm. The combination of quiet tuned pipe, higher pitch prop, lower rpm and better props will let you run a screaming fast pattern plane without offending the neighbors. Basically, you want a setup from just before turnaround or the early turnaround period for fast and quiet.


Mark