Ive copied my reply from the other forum incase you missed it. I have flown this model many many times and it is perfect when the correct CG is used.
With all your fuel ahead of the CG.. I would balance the plane upside down with the tanks 1/3 full. With gear up or down depending on which way the nose gear folds(i cant remember)
98mm is good. 100mm is perfect. Balance for 98 and if you go less than the 1/3 in your tank your CG will move back to the 100mm mark(hopefully not more)
Nice install BTW
In regards to the Video posted in post #15.. Clearly it was tail heavy.
Here's how my70mm(yellow one) flys with the correct CG(its the same plane as in the video above) My 90mm Version flys the same way(Copper one)
http://www.youtube.com/watch?feature...&v=lv8gZBhPx5I