I have found a solution that has really surprised me. My first Ucan do 46 I was running a OS.46FXH with an APC 11.5x4 with good results. Lost that bird to battery failure in the air. Now I put an OS.50SXH with a 12x4 and Hobbico tuned muffler on the new plane. The plane weighs 5 lb 14 oz balanced at 5 3/4 it is the best combination yet. The plane hovers at half power and comes out of the hole like a 40%er. The heli version of the .50 has a lot more power than the airplane version. And the larger head keeps things in the cowl cool. The carb is built with midrange performance in mind. If you think about it everything a heli needs we need doing 3-D. Stay cool in a cowled in low airflow installation, Excellent midrange and tons of power wide open. I'm at 2000 feet MSL. Another bonus of the heli is you could run 30% nitro with out any fear of the engine not liking it. In fact the instructions say to run 15-30%. I'm running 15% Powermaster in mine. I know it sounds far fetched but I would put the vertical performance up against any U can do set up I've seen yet. The real benefit is the plane is under 6 lbs. This keeps the wing loading so light the maneuverability is unreal. Light wing loading is the best attribute to the U Can Do .46. Once your over six pounds all you have is a lead brick that can go straight up. I'm into airplanes that can fly on the wing not just the prop shaft. Putting Saito 100's on a .46 U Can Do will kill the wing loading. Might as well take up model rockets. They will fly very similar. Jason