The Profi is probably happy to 40k, it's a robust little devil. Since it's open exhaust I might be better off with crankcase pressure as CP suggested, but the runs were pretty good so far I thought. It goes rich for a few seconds at the end, I point the nose up and get some height.
I see the props are $5 a piece, I had forgotten. The value depends on how you price your time finishing the darn things.
The model may handle a little less diameter, next spring time to experiment in earnest.