i actually happened to call AmericanMuscle.com recently about this. He recommended me to get 3.73 if i was really looking for the fastest gear possible on a daily driver. Anything above he said would be to much. From what i heard your gas mileage goes down 2-3 mpg but im not sure if that's just b/c people cant keep their feet off the pedal
. plus a cai or tune or a tb would bring the mpg back up anyway.