I moved my Rx and battery forward - they reside in a little slot next to the fuel tank, as close to the firewall as possible. I also moved the throttle servo forward to a spot next to the fuel tank. This must have helped a bit, but I still had to cast a lead block to fill the entire weight box, and I had to add some lead to the inside of the cowl. I have a .72 Saito installed, so less weight would have been required had I opted to go for a bigger motor.