The reason for the rear sprocket change was due to the size of the front sprocket. When we went to the 16t it was to large and actually hit the rubber mounting bushing [ DRZ400S].It would have destroyed the bushing in a block and a half ride. the shop that changed it had a computer program that allowed you to enter front or rear or both sprocket sizes and showed the results in final drive ratio and mph. The Ninja 250 site has one on line in the FAQ section. It's interesting to add in different ratios and see the results. You Can tell the difference on the RPM and top end MPH on my DRZ, not a large difference but noticable. CMS
