After I get my exhaust system done, I am thinking about upgrading the gears in my car (03 GT). Which would be better for a daily driver that soes half hifghway and half city? I'm leaning towards 4.10's, but thinking 3.73's for fuel economy on the highway. OR does it make that big of a difference since 5th gear is mostly worthless unless I'm cruising at 90mph on the highway.

 

what ratio does your car have stock? (Sorry, i'm not too familiar with the 4th gen's)

 

I'd go with the 4.10's, unless you plan significant power later on.

 

From the looks of it gas is not an issue. I'd purchase a radar detector!

 

I wouldn't get more than 3.73's if you do much highway driving. you could try the newer 3.90's.
4.10's are too much for my liking but that is just my opinion.

 

Yeah, that 250 rpm is a killer.

 

Stock '03 gears are 3.27. Swiappingin4.10 = More than 250 rpm's difference
At 250 rpms more a minute that quickly adds up over 100K miles.
Putting 4.10's in there is probably fine is you want them , but just be aware of the bigger picture.

 

I'm thinkin he meant 250 rpms between 3.73 and 4.10. Not between stock gears and 4.10's.

 

Yeppers. 250 rpm between 3.73 and 4.10. Not much of an issue there.

3.27 is about 2200 rpm at 75mph.

3.73 is about 2500 rpm at 75mph.

4.10 is about 2750 rpm at 75mph.

All rounded a bit, but close enough for comparison. And, really, 550 rpm should be about 1-2mpg based on what I've seen with my own vehicles. But, that's on the highway. 4.10's should be better on gas in the city.

 

i love my 4.10s. i would even consider 4.30s