how they compare at 10K RPM i don't know. i'm talking about 15K+ with 7"-10" diameter props. only noticed it because i was bench running a couple of engines with a very quiet multiple muffler setup. the fact that they run a bit faster despite the much wider tip must mean that they're flattening out...this could be the reason that they're quieter.

but then what happens when they unload in the air? don't know as the after muffler stays on the bench and the exhaust is all i hear. either way they don't perform as well as the APC.


dave