David,

excellent link to your tach tests on the S40. I have an identical engine which I plan to run with a 6.5cc muffled Macs TP. It'll be interesting to see how much can be picked up RPM wise. I'm interested in three props: 10x6, 10x7 and 11x5. It'd be great if I can get 13.5K on an 11x5 w/ TP!

Powermaster would be 10% or 15%?

Rusty, sorry for temporarily diverting the thread.

David.