andy,i put blue bird max servos in mine..big enought to ballance the 4stroke i had at the front.and loads of torque.flys very well.unlimited vertical lovely sound and a very tame elevater.i put 30%expo on it thinking it would be twitchey but then took it off again.goes in the car fully setup...perfect..does exactly what is says on the tin.I put a futaba pcm 146 ip in it to save glitches on such a small thing...love it...chris