OK, when my helicopter is at a certain RPM (not sure how fast) it makes a really smooth humming resonace but doesn't have too much power. When I raise the head speed I belive it is going on the pipe because it gets much more power but the engine gets rougher and makes the tail do a random, very fast micro wag. The transition from the smooth resonating hum to what I think is being on the pipe is VERY rough. The tail makes it look like I'm getting hit by radio interfearence it gets so rough and random, once it clears that the helicopter flies fine but still micro wags.

Any idea on how to fix this and what is causing it. I REALLY like the sound of the humming resonance and wish it made that sound when it was on the pipe. I'd even lower my headspeed to get it to do that while in normal mode!! It makes a sort of waaaAAAAAAOOOOooooM sound every 1 to 2 seconds. Sounds like the engine is running perfect when it happens, its just a little low on power and I'm afraid that the blades might over speed a little which will put me into the rough point at a bad moment.