I've been flying mine for a few years now. I have great performance with an 11-7 on clean pattern style planes. For a sport plane, they have given you great advise on a 12-5 or 12-6. The engine will make plenty of power, run nice and cool, and give you nice, controlable power on your plane. The larger props are too big for that motor and will make far less power and needlessly over work the motor.