AudiForums.com - 2001 S8 Steering issues need advice

My 2001 S8 has developed steering issues, as much as I hate to admit it the power steering fades when I am turning right and is more or less viable when turning left. This occurs at any speed therefore speed sensor issues are ruled out. My mechanic, who is research and tech savy for the most part indicated that this will most likely require the replacement of the entire rack and pinion assembly. He also indicated that if the steering failure was not biased to one side this would be less problematic and require the replacement of a hydrolic component/valve. Accordingly I have a couple of questions:
1) Has anyone had this problem and if so what was the outcome?
2) Is my mechanic correct in the seperation of the two issues depending on diagnosis?
3) Cost???? what am I in for? not that that is going to keep me from doing it

Any help is appreciated
regards