If my figures are correct the YS .91 and 1.10 are about twice the weight of a Saito 100, that's about 19 oz more. Seems a Thunder Tiger .91 will get you an extra 6-8 oz and have enough power. Engine would cost about $100 less than the Saito and about half as much as the YS 1.10.

I know the TT 91 can't compare to the YS in power, but should be close to the power of the Saito 100.