First off I want to introduce myself. my name is Josh and I live in PA. I recently picked up a 2003 quad cab hemi. I believe it has the 3:73 gears in it im not sure. Its lifted 3 inches with 35x12.5 nito mud graplers sitting on 20 inch rims. Im getting 8.4 mpg. I want to increase that alil. Thinking of a throttle body spacer and cool air intake. I dont think those alone will raise it too much or I could be wrong. I have been told that the 4:10 gears would give me a good increase. Heres my problem. I dont know anything about gearing or buying them, or even what to look for to buy and where to buy it. Any help/input I would greatly appreciate. Would the upgrade help with mpg? Thanks guys.

 

Save your money on the TB spacer. They don't do anything. 35" tires, you probly want 4:56. Usually 31" and under 4:10 gear. Bigger than 31" 4:56 or 4:88. Free mods include TMR and the Power wire mods. Look them up, there is plenty of DIY info. CAI helps with mileage. But big tires and being jacked up is hard on mileage.

 

And I have not seen ONE person who did something and got substantial better mileage.