The one in [link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=117]RCU Review[/link] flew great and fast with a YS 91FZ four stroke. I have a YS 110FZ in mine, and it definitely does not fly scale. Rolls and huge loops are effortless, and the plane lifts off the runway at half throttle. The plane weighs less than 12 lbs with plenty of wing area, so any 120 4-stroke will haul it around just fine.