What with 3.73's?
 

What all do I need to buy for changing from 2.73 to 3.73 on my 99 z28? Some local guys said I would need a programmer because my speedo would be off. Is this correct? Or do I just need the gears and an install kit?

You'd need to have it reprogrammed for the new gear or the speedo will be off.

You would need an install kit, fluid, etc.

Make sure you are buying 2 series gears.

This is an a4 also.

You will need to have the PCM reprogrammed, for it uses the MPH/RPM to correctly shift the auto transmission.

I upgraded to 3.73's and a Y3000 TC, and for the week I had to drive it until tuned, the PCM did not know what the hell was going on, I experienced idle hunt, premature shifts, down shifting at freeway speeds (my personal favorite), and a variety of other malities that were corrected with the dyno tune.

SteveC :)

How did 373s and a 3000stall do? Im thinking about same thing, just need convincing on DD

It changed the vehicle completly from the stock TC and 3.23 gears, HOWEVER, if I had it to do all over again, I would have gone to a 3600 stall.

SteveC :)