jgraham10, the YS 1.40 should be awesome in this plane. My buddy has a YS 1.40 and says it EASILY out-powers the Saito 1.80. I'm sure you'll be very happy with that combo. I've heard the Saito 1.50 is just not enough for this plane. I have the Extreme Flight Cap (nearly same plane) and I'm still torn between Moki 1.80, Saito 1.80, and OS 1.60. I've read all the threads, but still undecided. I really like the sound of the 4-strokes and have several other planes with them, but wonder if I'll be happy with the Saito 1.80 power in this airframe. It sounds like the OS 1.60 is about ideal, but I'm not sure if I'll like the sound of the 2-stroke. Moki 1.80 sounds like more power than is needed, but balances the plane easier than the others.