I've been flying my4*60 for 3 years now with a Saito 91 and an APC 14-6 prop. Definitely a good combination. If I had it to do all over again, I would opt for the Saito 100 which wasn't available at the time. This combo makes for good sound, smooth idle, excellent throttle transition and smooth performance at ANY throttle setting. Mine will hang on the prop but will not pull out vertical except when running 30% nitro on a cold day. I gave up the 30% and run it on 15% now to save money. Balance is excellent without any additional weight with the Saito .91. Perhaps a little pricier than a comparable 2 stroke, but well worth the price in my opinion. Well, that's my .02.