I had to add about 2 lbs or less of lead. But keep in mind I used the stock mufflers, 2 servo,s out on ythe motor box for choke and throttle, 2 1800 mah batterys inside the motor box, and a large prop hub out in front . My recommendation, move as much as possible out front. Even my retract valve is right behind the firewall. Hope this helps. Working on gear doors now,. Jon N