A four stroke is not hard to tune in my book. The Magnum four strokes have a better reputation around here than the two stroke models. If I had a 46 two stroke already, then that is what I would use. My flying buddy has the Senor ARF with a OS 61FX. Its really too much engine but it needs the weight to balance correctly anyway. So he flies it at about 1/4 throttle or so. He has thought about putting a four stroke in it, but would just rather fly it instead of working on it.