Crunch29, I would suggest calling Baker Trans. to get some help with your question. 1-877-640-2004. (info@bakerdrivetrain.com). They have a RPM calculator in their website. If you know the diameter of your rear tire, and the amount of teeth on your pulleys you can calculate your RPM at any speed. Also their customer service department is very helpful. They will be able to tell you if you need to change your belt depending on the pulley changes you might want to make. Other guys on the site have commented on this before. My only experience was with my 95 Heritage. I went from the stock 32 front pulley to a 30 and still used the same belt. Baker told me that if you decrease your front pulley by one tooth you would have to be able to adjust your belt .125" towards the rear to keep tension. (again this was on my heritage). I hope this helps. CAHDBIKER