I've had one with a Thunder Tiger .46 in it and another one with an O.S. .70 Surpass on the nose. Both flew absolutely fantastic, but the 2 stroke was a better match (and I usually prefer 4 strokes). Absolutely fantastic flying airplane and goes together very well. Use care when cutting out the half circle on the firewall for the muffler tunnel, took 4 stitches to close me up when I got careless.