He was talking about regearing the rear differential to a better ratio, usually the 3.7 has 3.55's and w/ the manual it's a good ratio for mileage and you can downshift when you need some more grunt. I regeared mine from 3.55's to 4.10's and it was a hassle due to a bad gears and/or a bad install. It's a more costly mod compared to an electric fan conversion or any of the others I listed and can't easily be undone. If I were to do my mods over again I would have skipped gears and just had the carrier swapped to a limited slip. The only reason I considered gears b/c I wanted better traction and was told the cost for labor would be the same for the carrier swap and new gears. I'd only recommend regearing if you stepped up to bigger than stock tires and felt like you had lost a lot of power.