I had a similar issue with my yak last week. The whol time that I've been running 4 cell I only fly with 25-75% throttle. I decided to do a low altitude,high speed pass ( I was at the red bull air races the week prior, so I was inspired...) Went full power and there was so much torque that I twistedthe motor mount. Luckily there were a few splinters holding it together and I was able to land safely. So now that the parts are here I'm gonna see if there's a way I can beef it up so that doesn't happen again.