I built mine stock, with flaps and the conventional wing. An OS .46FX was used to power it. It is a good flier and the flaps add fun to the flying. As far as modifications go, just make sure you bolt the nose gear bearing to the firewall. Plan ahead and add the blind nuts. The instruction book calls for screws for the nose wheel bearing, but a less than perfect landing on the nose wheel will pull those screws right out. In my case, not only did the nose wheel (and bearing) break loose, it was propelled through the wing which gave me a little work in reconstruction.

BTW, another club member built the "Contender" and powered his with a ".61". His didn't seem to fly any faster than mine with the ".46".

DaveB