cammed99gt

The 200rpm diff.is going from 3.90 to 4.10s.Just say u get 22mpg with the stock gears and it mite drop to around 18-19mpg but the first few weeks it will be much lower because of the feeling of gitting on it all the time and not keeping your foot out of the gas lol.And for normal driving around town it mite go up 1 or 2mpg

Stang9946

3.90 ftw!

SINISTER

Get 4.30's and don't look back. They made my car so much more fun to drive.

Mustang_NTriangle

I just installed 4.10s in my N/A DD car it is nice, but I also miss pulling car to 60 in second gear. Today I had the car in 4th gear approximately close to redline which is 5750, I think I was about 5500 RPM at 100 MPHs. It all depends what you are looking for. I would say if you go to the track alot 4.10s would be good or 3.90s.

With 4.10s you have no slop in revs but for all around DD I am thinking 3.73s would have been better choice for me since I do not go to the track.

It seems like you have your mind made up with 3.90s but as far as gas mileage I am about 17-18 miles per gallon vs 19.

cliffyk

I drive 500 to 750 miles per week (mostly on I-95, 10, and 75 in Florida and Georgia), and am not at all disappointed I went with 3.73s. On average they cost me 1.0 to 1.5 mpg (a solid 24.0 down to 21.5 to 23.0).[/align][/align]Also,after driving 3k miles with them I am certain that having engine spinning2800 at 80 mph (w/ 4.10s), rather than 2500 at 80 (3.73s) would wear thin after a while. It is of course a factthat it's "only 300 rpm" more that the 3.73s, however I know that after 250 miles on I-10 it would become annoying.[/align][/align]So, as other have said, if you don't drive a lot and can live with a 3 to 4 mpg hit, go with the 4.10s; otherwise I think the 3.90s or 3.73s will make the most sense--BTW, 80 with the 3.90s will be 2615 rpm or so...[/align]

MaKaVeLi

what you guys consider for automatic gear?

Mustang_NTriangle

Auto definitely 4.10s you need that extra power...

01GTCONVERTABLE

I bought the 3.90's and the master bearing kit from American Muscle. I'm putting them in tomorrow. I'll let you know what I think.

02 GT

4.10's FTW

Jexey

4.10's get the master install & bearing kit from americanmuscle
end of story