Great topic, as I have already placed an order for the 12 tooth sprocket. I'm currently riding with 13t/ 46t and all is well, except when I climb steep hills. Especially wet ones. When I can't get a running head start up the hill, the rear tire will start to spin. If I let off the gas "a little" the bike bogs down and stalls. I thought about going to a 48 to 51 tooth rear, but that does not address the SECOND issue I have when riding. I've been riding the same awesome course and progressing. When I put the bike in 3rd gear, it wants to go too fast and sacrificing the torque required to maintain stability! So, with the 12 tooth front sprocket, and 46 t rear, the calculations indicate the an approximate 35% increase in torque, and a 35% decrease in speed, from the FACTORY 14T/ 40T set up. I never ride over 55 mph on the roads to get to the dirt. On the dirt. 30-35mph is hauling, to me. I don't want to do it in 2nd gear, winding out the engine.
I'll have to remember to let you guys know how it works.