For what reasons are you looking to go to 4-stroke? If its to fly 3-D better,forget about it,a good running,over-powered 2 stroke will do an excellent job. Ive been there,I switched a few years back when a lot of people thought 4 strokes with larger props was the way to go. I have now gone full circle and back to 2 strokes,now that I know a little more and my skills are better,I'm doing the best 3-d I've ever done, and the sky's the limit,sometimes,the ground is the limit.