I have a few questions:

1. What gears are stock on my car now? (2002 Mustang GT)
2. How much improvement 0-60 and 1/4 mile time will I see with this mod?
3. What gearing is best if I drive 700-900 highway miles a week?

From what I hear, this is the best mod for the money. The only other mods are Flowmaster 40 series, air silencer removed, and k&n filter.

 

3.27:1

a bunch on improved tracks. street depends on your tires and launch skill. makes a world of difference once you're moving.

that's up to you. I don't personally like 4.10's, I like 3.73's but to each their own. You'll probably like either but I'd go with the 3.73's for that little tiny bit of added mileage.

It's the best seat of the pants noticeable mod for the money. Make sure and get an Xcal2 to reset your speedo or you'll be putting lots of miles on the ticker that you didn't actually drive.

 

That's a lot of highway driving. Max would be 3.73's. I believe that with 4.10's at 70mph would put your car at 2,700rpms, which is going to kill your gas mileage. With 3.73's you'll be at around 2300-2400rpms. I was also considering 4.10's, but now i'm set on 3.73's. What's the point of getting 4.10's on an everyday driver if you're never going to hook the car in 1st gear.

 

Look here:
http://www.modularpowerhouse.com/for...ear+calculator

 

id go w/ 4.10's...cause on the the gear calculator it says that w/ 4.10's @ 70 mph your at 2300 rpm in 5th..right where the rpms should be while cruising...if you need to speed up you dont need to downshift to get in the powerband cause your already at the begining of it which starts @ about 2100 rpm

 

who honestly cruises at 70mph on the freeway?

 

I have 4.10's and only turn 2300 RPM at 70. Traction is not that big of a problem as long as you dont launch at any higher than 1300 (but who launches there?). As long as you are rolling in first (like if you are at 2000 rpm or higher) you wont lose traction as long as you have decent tires, its only when you launch. If you are really conscerned about traction, just buy a set of DR's.

 

What kind of tires do you have? I was thinking of running nitto dr's. If i don't have to then that would be great.

 

I've got 3.73's and i wouldnt go with anything different on the highway with my 18's on at 70 mph i'm doing about 2100 rpm which is perfect for me. I run BFG DR's especially now after a cam install... I would highly suggest 3.73's and also i would recommend Richmond gears... I got Richmonds and i love them there is a very very slight whine which is notorious for richmonds from whta i've heard but its a repuatable company that been around forever...

 

I have experienced 4:10 and 3:73 and I prefer the 4:10's (hence that is what I got) I dont drive as much as the original poster but I drive a fair bit on the highway. I think the gas mileage comment is redundant. A mustang is not gas conserving but, if you are that concerned about your MPG you can get some underdrive pullies and longtubes to make up that +/- 1 MPG.
Cheers
Cooper