I flew mine with a 46FX and with a 11x5 prop It would go vertical out of sight. This is one of my all time favorite planes, I like it better than my Ultra-Stick! But I also have the Magnum 46 XLS and it is just as powerful and sweet running as my FX. So with that in mind either the OS or Magnum would give you the performance you need. But if you were going to buy the engines new I would go for the Magnum and save a few bucks!