Im not real knowledgeable about gears ratios, but I recenctly lowered my sled top gear by 2 teeth and left the bottom gear alone. It made a huge difference in my sled, but what would you get out of changing the lower gear? Sorry if this has been covered, Im not gonna change it, I am just curious to what it will accomplish, I would think more teeth will rotate the track more at a given rpm, and a smaller would slow it down right?