i have the cox waco with an os 120 4 stroke, seems to have plenty of power, the wheel pants were a problem but a flying buddy brazed the brackets and they are fine now. the cox instructions left a lot to be desired. go to tower hobbies and you can down load the assembly instructions. they are a lot better than cox. i like the great planes covering better over what ever was used on the cox. if doing it all over again, my choice would be the great planes version.