[jlaw73]

I own a 05' Mustang GT automatic and want to upgrade the rear end gears. I think in stock form they are 3.31. I'm thinking 3.73 or 4.10.

Would 4.10 be too much? I drive about 30 miles per day on the highway.

Other upgrades ar: SLP Loudmouth Axle-Back, C&L intake & Diablo Sport Tune, & Eibach Pro-Kit Springs

 

[psfracer]

I also have an auto with 3.31's on a 27 inch tall tire. I am installing 4.10's next week....going to the track again with no other changes...so if you can wait, I can tell you rpm difference (which you could figure out mathmaticaly--which is about 600 rpm higher). For me this means 2100 rpm at 70mph to 2700 rpm at 70mph. I can also tell you exact difference in 1/8 and 1/4 mile et when I run at the track with the 4.10's


There have been many other posts on this subject, but basically if you have an average size tire (26 or 27" tall) and you are N/A, go with the 4.10's. HOWEVER, if you plan on going with a supercharger, many people have suggested 3.73's.

 

[discofan]

Dear Jlaw73,

I have an automatic with the 3.73s installed... Good performance gear for all around play...

If you intend on supercharging someday, then stay with the 3.73s, but if you drive in the city, then 4.10s would be for you...

Don't forget to go with wider tires in the rear because with either of these gear sets will spin the tread off in no-time!!!

Dave