Just a summary answer what does retrofit means exactly? is it like changing steering wheels or are you just realligning the steering?
thanx and sorry if this seems a wierd question
When the 325/330 first came out, BMW decided to up the boost on the power steering to "assist parking". Prety much all the car mags and a large number of the purchasers complained that the steering was now too light. Some went so far as to call them "The Ultimate Parking Machine". Enough of a noise was made that BMW decided to offer to replace the steering rack and other various, related parts on these vehicles for free at the owners request. This is the steering retrofit.
There were debates over weather all 325/330s got the lighter steering or just those headed to the US. There was also speculation that the boost was increased to compensate for the added weight of the AWD system on the xis since there did not seem to be a problem with them. If you want more detailed info or you want to read some of the debates (read near flame wars) on the subject, do a search on The ORG.