I have run into the same problem before. it was with tower pro micro servos on a Hyperion Sniper that had poor aileron throw. The aileron horn supplied with the plane has one hole and there is really no good way to add more because of the shape. The included arms with the servos just weren't long enough to give adequate throws on high rates. Since I have found no aftermarket arma that will work with the servos, extending them seems like the logical choice.