guns- be able to select how many bullets up to the max in each gun you want. for example you could take 0 bullets in the tail gun for the 110g2 and not have to kill your accuracy shooting them all off.
fuel. instead of 25% 50% be able to type the number of gallons you would like in each tank.
I believe this would make the game more fun and the planes more customizable. rewarding players who customize their fuel and ammo loads well. perhaps adding another dimension to an already great game!