I have been running a 3-speed overdrive and have found it to be a poor choice. I have the same opinion as others that have tried it. First gear is too high and the spread from 2nd to 3rd is too wide. It is a 46% drop. That requires revving to max RPM in second gear and bogging into third with minimum throttle until there is enough power. Adding the 3000 RPM spring would only be a patch for improper gearing. I have decided to swap to the M5R2. I would like to share what I learn as I go.