How heavy is the os 120 compared to say a Saito 100 or ys 1.10. I wonder if your a little too heavy with that engine, I have flown them with the above two mentioned engines and not noticed a wing drop. Just a thought because I flew a Funtana 40 with a 100 and it dropped a wing like crazy, but with the saito 72 or 82 it didn't drop as bad. The perfect match for this plane is a ys 1.10 in my opnion. All I can say is with my plane I can fly level a full power, cut the trhottle right in frnot of me a cuople feet off the ground and pull full up into a wall that should rip the wings off and I havn't noticed any rolling out problems.