Hey I added 2 inches of rudder on my SE and 1 inch of counter balance. I think this is the easiest way to get more authority out of the rudder along with extra torque servos (70oz+). On my SE I put a Saito 72 with a 13 X 6 APC prop. My CG is around 4 1/2 inches back from the LE. My SE will do a Knife edge loop! Sigs recommended throws and CG:
Center of Gravity: 3.5" Back from the wing's leading edge
Control Throws- Low Rate High Rate
Ailerons: Up & Down 1" 1-1/2"
Elevator: Up & Down 1-1/4" 1-3/4"
Rudder: Right & Left 1-7/8" 2-1/4"
I think the extra power has more to do with knife edge flight than anything else.