I too switched to a bigger prop. 15x6 APC The 14x5 Thin apc was spooling way too fast on the 91FX. On extreme high speed passes I was getting some minor buffeting. Not a true high speed stall but getting uncomfortably close . The Edge's control surfaces are too big for high speed and too small for decent 3/D. So I'm going for the best sports flying prop/speed combo I can.