I know this is an OLD thread, but I just happened to stumble across this post a few weeks ago and decided I needed one of these. It is a great looking plane. I do have one question though. Im using the 55AX with a pitts muffler and a 2500 mah 6v nimh battery. With battery mounted in the location on the firewall just behind the engine, my cg is quite nose heavy. Using a Great Planes cg machine, Im at 92 mm. I also tried a 4.8v battery in the same location and it helped a bit, got me to 101 mm. Id be happy to get somewhere between 110-115. I just found it odd that mine is so nose heavy when I see many others have put larger engines in and still had the battery up front and balanced out fine. Has anyone had to mount their battery under the elevator and rudder servos running the 55? Moving it there is fine, its just a lot of extra hassle if I need to get to it.