I tried mine on a speed 400, 3-1 gearing, 2s li-po, and 12x6 prop and wasnt impressed. The thrust of the 400 setup is 2oz more than the stock setup, but the 400 setup weighs alot more than the stock so 3d performance doesnt increase, however mine seemed to fly a bit faster.

I burnt out the stock motor and replaced it with a Great Planes t-370, performance seemed to increase quite a bit. For the first few (maybe 5?) minutes of a fully charged pack the plane does 3d pretty good, you can give it full throttle let it go and it will accelarate vertically.

I have no problems with tail heavy flight, but depending on how you launch it, it might start out tail dragging. If you give it an upward underhand toss it seems to start out tail dragging and continue to fly like that until you level it out, but if you give it a level over-hand toss it seems to fly level from the get go.

From my experiance with the stock setup it sounds like yours might be overweighted. I have mine balanced at the recomended point, the battery is at teh leading edge of the strut up against the top of the wing. Receiver is mounted against the top of the bottom wing and about 1/2" from its Leading edge. ESC is right by the wood LG mounting block. Aileron servos on the bottom of the bottom wing right over the spar, rudder/elevator servos are about in the place the book shows, and my wires are just hanging everywhere.

Im surprised yours seems so underpowered, I even have a bunch of extra dead weight on mine and it still performs good. I put 1/2" scotch tape on the LE of each wing, added velco, using the LG, using a big heavy duty y-harness, added plywood reinforcement to the motor mount, added sliced up dowels to the front of the plane for reinforcement, added CA'd kite string to reinforce the LG, has all kinds of tape holding stuff in palce, and I even built mine with Epoxy!

Maybe you should give the GP T-370 motor a try, seemed to really boost mines performance.