The best prop I found on the FSR was a Rev Up 11x 7 3/4. The second best was the APC 11x8 on my old Dirty Birdy. By the way the FSR ans the SF were higher quality and longer lasting thany of the newer engines that OS is putting out. As an example it was not uncommon to get 14,500 rpms on the ground with the APC 11x8 as opposed to the 11,500 your getting with the FX on the same prop. The only advantage that I can see with the FX is that you can get parts for them. But as cheap as they make them now, you would be beeter off going with a Tower 61 and getting better performance.

Just my 2 cents for what its worth.