I think you will find that equivalent sized 4 strokes can turn a much larger prop with a lot more pitch. My Magnum 52 with the right prop demonstrates about the same power as a good .40. Using the high ptich props makes a good idle even more important in order to keep landing speeds down so a good quality 4 stroke is preferred. My Magnum did not exibit good idle quality until it was returned and repaired. Ifind it acceptable now.