rdmonster, I have the e-flite brushless 400 4200kv on my ultimate and it fits without any trimming of the foam. It has unlimited vertical. It has soo much power that if you go full throttle on a fresh battery it tweeks the fuse so bad the plane flies uncontrollable. Just make sure you use proper throttle management. It is a great combo. I have had about 100 flights with this combo and it is still going strong.