So I'm about to finally get some gears. The granny gears just weren't doing it for me. I know there are millions of gear threads out there, I just wanted to ask you guys and see if ya'll had any different opinions since the last gear thread. I know I don't want 3.73's because my buddy's 01 GT has those and it didn't feel much faster than mine. So I'm thinking 3.90's or 4.10's.

Now before everyone says go 4.10's or die, this is my DD and I don't want my MPG to take a major hit. On my last tank I averaged over 26 mpg, but I drive like 75 miles a day on the highway.

I'm leaning more towards 3.90's. How much will these drop my MPG's, city and highway? And anyone with 3.90's speak up and tell me what you think about them.

Also, I found a Mustang only shop that will do gear installation and bearing install for $200 bucks

 

Go with 4.10s. 3.90 isnt a big jump from 3.73 to really noticed much. 4.10 or bust especially on an auto

 

Go with the 4.10's. I hear more and more people with 3.90's or 3.73's saying that they should have gone with the 4.10's!!

 

4.10s. Just in case it hasn't been mentioned yet.

 

You probably won't see very much difference in mpg between 3.90 & 4.10 gears.

I will be changing gears again from my 3.73s to 3.90s(note: I swapped from 4.10 to 3.73 about 2 months ago), but that is all about rpm at the end of the 1/4. If you don't race your car at the track you won't have any issues with the 4.10s.

GOOD LUCK with whatever you decide!

 

Are you saying 4.10's are not good for the quarter mile because of your RPMS at the finish? What gear are you in and at what RPM at the traps???

 

Be aware that with a slushbox you will need your tune modified to properly mate the auto tranny and lower (numerically higher) rear-end gears...

 

When I was n/a I started with 3:73s, wasn't enough so went to 3:90s, still wasn't enough so went to 4:10. I ran the 4:10s with my vortech and procharger and didn't really have any issues with them. Once I went the kb route I went back to 3:73s as 4:10s were a bit much, I'm still undecided but I may go from the 3:73s to a 3:55. 4:10s are the way to go for an n/a car though, especially an auto.

 

I have 3.90s in a 2000 gt 5 speed and couldn't be happier. I get up to 20 mpg city and 26ish highway. In the 1320 I finish at 5800 rpm in 4th. I found 3.73 weren't much better than stock and 4.10s cost me time because I had to shift into 5th. These cars shoulda come with at least 3.90s from the factory. Mine are motive and don't whine whatsoever. Install is key.

 

+1, 4.10s

I got over 300 miles to a tank while DDing my mustang with 4.10s.