This is my first post under the new rc universe, so bear with me. I have had two 4* 60s and powered them both with 75 two strokes. The first one was a Supertigre and the other is Tower hobbies 75. They seemed to have plenty of power with a 13x6 prop and I think the 90 would be a little overpowered. However I am no expert on this as I am your every day sport flier.