Nik, here is a link to the P5, the 14x12 is the smallest recommended prop, the engine is designed to run in the 8,000 rpm range for quietness and to meet European noise rules. I like quiet so I use it the way they intended. Others have tried 14x6 props and were disappointed. http://www.webra-austria.at/motor.ph...r=AERO&lang=EN