ASP or Magnum XLS 52 (same engine) The strongest of all conventional 50 size engines and it runs truly great with some carefully tuning of the low speed needle. Mine powers my Katana profile and does tailtouches and can hover all day down at the deck and lately some hover landings too This just to confirm that the engine is very dependable. At 13700 rpm on the APC 12.25-3.75 with the Tower muffler it would pull your plane on floats out of the water quicker than you could believe. Cheap as dirt too