I know koni but not really into them,
Bilstein doesn't seem to have any for the rear of the car.
are their others out there?

Any particular reason for your distaste in KONI's?
They're a great shock with excellent ride qualities.

Both are available for the quattro model <a href="http://www.purems.com/products/category.php?CA=166&PA=7">here</a>