[PxTx]

Interesting to read that Ken. When I did my AAN S4 5 cyl turbo swap in my old 1987 Audi 4000 I had concerns about power steering compatibility. I was lucky and it all worked out. Dawing from my experence and yours, I think the real issue is probably flow, which prior to your post, I had not considered.

My original PS rack had a pump on it that was rated at 75 bar (which is about 1100 psi). When I swapped the AAN motor, the S4 had hydroboost brakes since it was a turbo car. I did not want to go hydroboost, so I kept my OE brake system. My original PS pump was too different to swap on, but I was able to grab a pump use in the later A6 that physically was the same, sans the extra pump segment for the brakes. The A6 pump is labled 120 bar (about 1800 psi).

My car drives great, but I am cautious not to stay on the steering lock when in tight turns. I've compared my car to stock cars and the steering is no different. I always wondered how the increase in pressure seemed to have zero influence on the steering responce and feel (doesn't feel any lighter than stock). After reading your post, I think it is probably due to wither having the same, or lower flow as the stock pump.

If that is the case, Mark's question really is interesting, as a possible solution. Thanks for sharing!