Cee Gee...THe Mayhem will weigh less than 7.5 lbs with a Saito 100. If you are anywheres near sealevel it will be fine on that plane. But I think you should run 30% in all 4 strokes but you'll be fine with the Saito. If you run it with 15% you can always up it more if you're not satisfied. The YS is the perfect engine for me but I'm at 4800' elevation. I think I get Saito like performance up here. I think the Saito would be a good choice.

Thanks
Barry