I used to run a 13-6 on the mds .68 and that ran really well. I know my buddy has had two mds 48s and both never ran reliable. It seems to be a luck of the draw on the mds engines. Guess I got lucky but my .68 is as good as any engine I've had. Right now I'm still a little concerned over all up weight the bipe is going to be. At 50 inches it's not much bigger than your standard 40 size profile but with the extra wing and structure, it may be close. I'm targeting 5 to 5.5 lbs ready to fly. If I can get there then the .60 engine will work fine. Of course......more is better.