I have over a hundred flights on my E-flite Ultimate and here is the trick. ( I love that plane... awesome!) Bump your battery pack forward maybe an 1/8 at a time, when you can trim the elevator so that it can fly upright and inverted without applying up or down stick, hands off. then the CG is set perfectly.

I discovered this because I use a TP 730 mah and Kokam 1500 mah packs and some flights it would balloon upwards (tail heavy) even when inverted. I never realized how much 1/8" change in CG matters with these little planes. The pack must be high too. The way to set the height is like it says in the instruction manual. Put a little hole in the fuse behind the prop and hang it on a wire. It should be perfectly vertical.

When you learn exactly where the pack should be by flying it don't worry about where the instructions said it should be, you now have it right for that plane. Make sure you put it on the sweet spot each flight. [8D]