RE: prop suggestion?
The rod, crankpin and rear bearing is the weak link in alot of cheap engines. The Magnum might not hold up over the long haul to 18,000 rpm......but the original poster wants to get max speed out of his engine. Don't over look thinning the blades as a way to boost power. I would also use up to 25% oil, castor will help the parts live a longer life.