I have to agree with the 10K RPM limit on the ground, as it will unload in the air and that will put it over the 11K RPM limit. Plus running a little rich will add to the life apan of the engine.

If your going for speed, go with the smaller dia. prop and the higher pitch. But keep the RPM, at 10K. I think that will give you a faster flying plane , if thats what you want. I am not sure how that works with the 4 cycle's and the limit on RPM's.

If you need more power or speed, it would be better to go to a larger engine.

sticks