I discovered that I need to keep the most mass forward as much as possible to keep the great tumbling stuff the Reactor does. I tried another motor out and had to rearrange my packs rearward. Not so good. Ruined the tumbling. Got a Neu 1509/2.5D and WOW! what a difference! Not only do I get unlimited performance, but the balance has worked out perfectly. There's still a little wing rock left upright and inverted, easily managed. Still thinking about adding SFG's to help in that department. Other than that it's an awesome intermediate 3D trainer for me. Very forgiving airframe, wish GP would make a 50cc sized version. I'd like to place my order now!