At the other end of the spectrum, my Webra .91 P5 turns an APC 14x12 at 8,400 rpm now with an hour and a half time on it and gets stronger each time I run it. This engine and its seemingly huge muffler are designed for exactly that, a huge prop in the mid 8s, on 5% nitro. It seems like American guys just can't accept that fact. And, Dar, the MVVS .91 comes very close to that.