That's surprising!!! I have a Zagi 3-C and it has a standard 4.8V 600mah pack. I also had Hitec HS-81 servos for the elevons, but needed nose weight, so after a while, I took the 81's out, and put in standard size Futaba S-148's. In general, Zagis need a significant amount of weight in the nose to offset all of the wing material that lies behind the CG due to the sweep of the wing. I am EXTREMELY surprised that your 3-C is coming out nose heavy. -Eric-