Another vote for the 12.25 X 3.75. I am not much for the funfly type stuff, but a friend is quite handy at turning his Magic into a helicopter. According to him, the real difference was switching to this prop. Same story...some guy sold him on it, and he will likely never leave it. To get a few extra RPM, he put a tuned pipe with it. It seems to be a great combo.

Zee