To me the best prop for this engine is an APC12.25x3.75 wide blade. Lot of 3D pilots use it. With a pipe and header mine is turning the 12.25 right at 14,000 and it will turn an APC 11.5x6 about the same. Either one of those two props are in my opinion the perfect props for this engine. A 12x6 is too big. These motors like RPM and you could burn it up before you know it with that much load on it. My G-51 is on a 4lb Little Stick. I will be flying it next weekend. Check out my thread on my G-51.

Something else... I bought a SuperTigre GS-45 and it doesn't seem to have near the power that the G-51 does. This motor is struggling to hit 11,000 with an APC 11x6 and my G-51 with the stock exhaust was turning 1600 more than that.