I currently 4.10s in a Duster 340 that engine wants the gear. In my 360 car I run 3.91s now soon to go back to 4.30s or 4.56 gears all you need is a LT tire of about 29-31 tall cuts into gear real fast. The 4.30s were the best all around street gear tall tires cut the revs and the car had a ton of response as far as people passing you wait until you hit a hill. Lesson learned use a quieter muffler As far as gas mileage I get the same with 3.91s as I did with 4.30s. Also my Duster should be getting lousy mileage with 4.10s and 25 tall tires I get 14 around town with a stick