Does anyone know if we already have the 4:1 bias ratio? Otherwise can we do a center diff upgrade like: http://www.jhmotorsports.com/shop/ca...only-p-46.html

I got this off wikipedia for the A4
http://en.wikipedia.org/wiki/Audi_A4_(B8)#Transmissions

The quattro permanent four-wheel drive system uses the latest Torsen T-3 centre differential, with a default 40:60 front to rear asymmetric torque distribution ratio (used first on the B7 RS4) as standard. (Previous A4 quattro models split torque with a default front:rear 50:50). The additional torque bias applied to the rear wheels helps mimic the driving dynamics of rear wheel drive cars.
Also this from wikipedia as well
http://en.wikipedia.org/wiki/Torsen

The Torsen T-3 will be employed as the centre differential in all future non-Haldex Traction Audi models with quattro four-wheel drive, current applications: 2008 Audi S4 (B7), Audi RS4 (B7), and Audi Q7.
If we already have the center diff from the RS4 (B7) I have another reason to love this car.....