My son flies one with a Saito .91 4-stroke and a 14x8 APC prop ... it flies like it's on rails and has unlimited (and fast) vertical ... nothing prettier that a huge, really huge, loop with snaps at the 90 degree points of the circle! Does it all yet lands pretty tame unless you get stupid slow. Some club members have ones with OS .46FX's and theirs flies great, too. But the larger Saito turns it into a real pilot and crowd pleaser! This plane just says take me vertical with rolls and a snap on the way up and then 4 point rolls all the way down! Or, take it high and spin it down for almost instant, thumbs-off recovery. A dandy plane.