Redwind,

The engine choice depends on how you intend to fly the plane and your budget. For all out performance and entry into pattern competition, I recommend either the OS 61 "Hanno Special" two stroke. Or the YS 91 FZ four stroke. I used to have a DC Killer Kaos which is virtually the same airplane (98% common parts) with the Hanno and it was a dream to fly.

For sport flying, good 2 stroke choices include the OS 61 FX, TT Pro 61, Irvine 72, Super Tigre 61 or 75. I'd steer clear of the YS 61 two strokes. While powerful, they're cantankerous. The Hanno is packs more power and is much more user friendly.

For 4 strokes, I'd go with a good 91 like OS, Saito, Enya, or Thunder Tiger. I'd be leery of the Magmun. I've read many negative posts on Magnum four strokes.