Good Point, O.S. .50 SX weight with #873 Muffler, is +/-17.26 oz, Webra .50 GT is 16.10 oz. Pretty close, but the Webra has the weight advantage, although the SX would not weigh down that plane much. I would advise against any of the .60 size engines for this plane. Just my $.02, Part of the fun in this great hobby is trying new things, so maybe I will order a Webra and give it a try, sounds like a nice engine. Good luck with your engine quest..........and remember above all-----have fun!!!![8D]