I have done many Echo's and they have great power and are easy to convert. The Echo is a 21.2cc and would be similar to the new G-20. I have used that engine in a Seagull Models 60 size Edge. Flew good but not a 3-D powerhouse. The Stihl is 25.4cc and would be a real nice engine to convert. I have a couple Stihls just no time to convert them.