Andy, I don't think that I'm qualified to answer that as this is my first YS engine. I would pose that question in the 'YS Club' thread, this forum. I'ts probably on page two. There are some with really great info and could supply you with a little more details. I believe the 110 has about 8% more power than the 91, but don't quote me on that, I could be wrong. Compared to the Saito 100, which I originally set up the UCD with, it walks all over it. Good luck, Joe