I've been out of the game for a year and I'm looking for a new engine. I've got my eye on either a Keep-Off 21-4, Keep-Off 21-4/S and a Mito 4. I'm looking for good fuel milage and a strong bottom-end. Can you guys tell me how these engines respond on the track and how their performance differs? I'm also open to suggestions on other Nova-based engines.

Thanks!