I don't know about the 650, but I just changed my Versys X 300 to 15T front, and 44T rear. It made the bike more comfortable on the road, and the lower gears still seem to have enough grunt for the light trails and dirt roads I'll be riding. Highway mpg according to the computer seems to be averaging between 65 to 70 mpg. Personally, I'm not fond of slipping the clutch because it makes them wear prematurely and can warp the plates if it gets too hot. I'm happy with the change in gearing, but YMMV.Hi. How did this change affected how the bike handles at low speeds? Need to use the clutch a lot? How is first gear? More or less usable?