I've had a few of these built from kits powered with Os 120 Surpasses. The only manuever I was lacking power on was a vertical snap roll. I could get through it, but it was hard to keep the airplane going straight at such a slow airspeed. I think the Saito 125 will work fine. I would skip the smoke. The extra weight will kill your performance and glo motors don't seem to give off much smoke anyway. If you want smoke, go with a gas engine on a bigger plane. Take your time building and make sure everything is dead straight and all incidences are exact. One of mine was perfect and it flew much better than the others that were "just good enough".