How much of a differance will I get from installing 4:10's in my 04 GT 5 speed? Also how much more gas will it eat up? Any idea on how much time i would gain at the track?

 

id say at least 3/10th in the 1/4 changing to 4.10's,but i dont know the profile of this 4.6 yet,so it might be less.

as for gas mileage,youll be really killing that if you get on it in the city..on the highway youll be running around 3500 at 65

 

hey andy just letting u know he wont be running 3500 rpms and 65 cause i had 4.10s in my 97 4.6l and when i was doing 65mph i was only at 2300 rpms. its not that much in gas mileage. i got around 18 mpg with the 4.10s. with a bunch of other mods but i swapped out the 4.10s for 3.73's because i was hitting 4th gear before the 1/8 mile marker. but go ahead and swap them out

 

just have both worlds put in a set of 3.90's

 

I got 22 mpg on the highway to Atlanta UNTUNED with 4.10's, all kinds of other mods including aftermarket cams. I rev at 2500 rpm at 75 mph (02 + GT's have a lower 5th gear ratio of .62 vs older 4.6's that had a .67).