I bought 3:90's for my '95(just go to the Motive website) i didn't look at gas mileage when i decided, i was thinking about where my power curve was atm and where i started to drop off... i'll get a good jump, and the 3:90's will keep me in the perfect RPM through the 1/4 ;10, 4mile. i don't care much for anything past 1320. but thats just me, and i've got the 5.0. most everyone i know running around with a mod car has either 4:10, 4:30 or 4:56. i've got a buddy with H/C/I '04 GT with 3:73's and he swears by then, then i've got a friend with a Nitrous '97 Cobra running around with 4:56's and he swears by them. so you need to figure out what you need, and why. THEN decide on the gearing.