I have the Saito 100. Almost too much power. Too much useable power anyway. I NEVER go over 3/4 throttle and even that is on a high speed vertical climb. If you have to buy a engine get a Saito 72 or YS 63. Dont get OS 70 Surpass cause even though it makes almost as much power as a Saito 72, it weighs nearly as much as a Saito 100. That is why I used the 100. I had it and the OS but after weighing them i chose the 100. In fact, if you wanted to go with the cheaper route, you could use an OS 50SX. It is a very light and very powerful engine. Or heck, even a Thunder Tiger 46. Pair either one with a 12x4 APC or the Saito 72 with a 14x4 APC and you will have plenty of power. Dont listen to these clowns saying that "You have to have a Saito 91 or 100 cause it wont fly on a 72 or 46 two stroke." Well GUESS WHAT. Yall are full of crap. Maybe at 6000 feet above sea level a 46 two stroke wont hover it, but nothing is as good at that elevation anyway. Oh, and this is not just my $.02, THIS IS FACT.