I had a 46ax with an 11x6 apc, in a Sig FourStar. It flew the plane nice, but really struggled on climbs and power maneuvers. I then installed a 55ax, with a 12x7 apc, and could not believe the difference!!!! Not endless, but great vertical climbs, and can handle almost anything. Handles great in the wind. The 55ax is a great engine.