Thank for all the advice/input. Choosing a powertrain is somewhat of a sensitive issue up here in Johannesburg South Africa. Altitude of about 5000ft above sea level puts a damper on the engine perfomance, thus I have bought a second hand 1.20 OS 4 stroke for my new cub. My club buddy very sucessfully flew his cub at this high altitude, in fact you can punch holes in the ozone layer with that power! Attached is the actual engine I will be using to wind up my cub - also OS 1.2 four stroke, once completed