airbusdrvr, the C.G. with the 3000mah 4cell pack is at about 420mm from the nose back. The manual recommends 415mm. I had to give about 1/4" down elevator for level flight. On my next outing I am going to try a 4000mah 4cell pack with the C.G at 400mm.
I am not using an adaptor for my 9x7.5 prop. It must be closer because I'm not using the spinner so no spinner back plate.