About how much of a boost would changing to 4:10 gears, how would it help my 0-60? not to worried about top end speeds

 

Depends on your current gears. But yes, 4.10s would give you a hell of a boost. As the gears get lower, the engine gains a mechanical advantage over your car. The engine doesn't have to work as hard to turn the wheels. This makes the car rev much quicker thus you end up having a quicker car. Imagine having a 1:1 gear in your trans and differential both... Every time the engine turned over, your wheels would turn over... This wouldn't work because the engine would turn so slowly (thus you would have no torque and the car probably wouldn't move).

Just be warned that your gas mileage will go uber south on the highway. Even at lower cruising speeds. I take it you have a 5 speed then?

 

no my car is automatic... will 4:10 not work in an auto? my car hasn't seen a major high way since i got it.... so thats no problem, and lol its a sixxer so i'll go from 28mpg to 20? that fine wilth me if its a good boost

 

You'll go from 28 mpg to about 15ish. Because instead of cruising at 2200, you'll cruise at 3200. The automatic is geared very low (the transmission itself). I would advise to go with 3.73 instead of 4.10 so that you don't demolish driveability. Most people go with 3.73 in the auto because the transmission itself is geared very low

 

how does a 3.73 compare with a 4.10?

 

Well obviously 3.73 will not pull as hard. But 3.73 in an A4 is PLENTY for what you want. 4.10 is gas mileage demolisher. 3.73 is still worse mileage, but not as bad as 4.10s lol. I have 3.42s in mine and I get about 24-25 on the highway.

Go with 3.73 or 3.42 in an A4. Don't mess with 4.10

 

ok, i'll look into both and when i get my car back i'll decide... also, is the rear end on my car the same as the other 1988-2002 cars? well besides the posi z28. Are the ring and pinions the same? I'm not sure but i think the rear end in my car is either 8 or 10 bolt? and is it the 7.5? thats the the gears i'm lookin at say...

 

I'd be more concerned with traction in first gear with 4.10s than gas mileage. But that's just more push towards 3.73s.

Even with a v6, your total torque multiplication in first gear would end up putting you sideways in an instant with 4.10s. 3.73s are much more manageable through first.
4.1*3.06=12.546
3.73*3.06=11.4138

To give you an idea of just how much those numbers actually are, in a t56 equipped car, first gear is a 2.66:1 ratio.
2.66*4.1=10.906
You still beat out the manuals with 4.1s, with your 3.73s.

 

ok i have a question where can i find the gears i need and where can i have it done or is not the hard of a task??

 

I don't know where your best bet would be to buy them, but I'd suggest getting it done. It'll be about 600 bucks for parts and labor, but it's the smart thing to do. Doing this install is hard, doing it right is harder, and doing it well enough that you don't get any gear whine (including doing break-in) is very hard.