Bobby ... 10x6 to 11x6? Heheheeee ... just keep the 11x6 if you want a bit more torque ... a Bolly 10.5x7 is nice. I have a Phoenix Scanner with a tuned pipe and a TT46 Pro, that throws an 11x6 as I want more torque to pull nice verticals. My Black Horse SU31 (SC46) is a little heavy so I prop it with a 10.5x7 for more speed ... all depends on what you want.

One way not to kill your engine is to check its temperature, when I played RC cars we kept it around 110C ... till today when I land the plane I will check on my engine temperature, of course I know what an over heated engine feels like so that helps.