Thats funny you should say head speed, I have 3 lipos, 3s 1800 25c, and 2 3s2200 30c, the 25c is turning rotor faster than the 30c batts, dont have a way check rotor rpm, I have 8 deg on cycli but the slowest roll rate, Align trex 450sa, 35 align esc, 430 motor, Futaba 401 gyro, metal head. took the carbon blades off, put the wood back on and this helped a little, the 25c batt is 5years and the 30c batts are 2years, need new ones, cell volt are still with in 2 tenths or so, I can hear the motor bog down when I punch the cycl, then the tail acts funny, pull slight neg cycl head speed comes back and then the tail comes back. When I go to filp or roll it starts quick and then slows down even faster.