I just finished my first kit, the PT-60. I really enjoyed building it. With a Thunder Tiger 61 Pro, and 600mah battery under the tank and against the firewall, it needed about 2.5 ounces of lead bolted on the bottom of the engine mount to balance. Is this pretty common with this kit? If we get a good weekend anytime soon, I'll get my instructor to test fly it and then see how I do on the buddy box.