Harry, that's good stuff you said, when I got my Webra P-5 .91 people had trouble wrapping their minds around the smallest recommended prop being a 14x12, (which it turns at 8,500 on 5% nitro) and the largest a 16x8. I tried that 14x12 on a SuperTigre .90 and it only could manage 7,000 and quickly got hot. The P-5 has an absolutely huge muffler.