I also decided to upgrade my flap servos. The 645MG have served me well in the past on flaps, but were not up to the task in this model. I installed Futaba 9155 digital s in their place. This is a 192 ounce servo. By raising the servo as I did , I was able to mount the push rod two holes closer in to the spline giving me a much better mechanical advantage over the previous setup.