http://cgi.ebay.de/BMW-BAVARIA-C-PROFESSIONAL-RDS-mit-zubehoer-Marke-Becker_W0QQitemZ330249436637QQihZ014QQcategoryZ142 59QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

what is the advantage of this on a US spec car?

wow, nice find.

http://wp1016621.wp027.webpack.hosteurope.de/fotost/f01175/c_professional_rds.jpg

That's the Becker/BMW Bavaria C Professional RDS indeed - one of the best units that were available for the E31. Alternatively you can get the single unit version - the Becker/BMW Professional RDS:

http://wp1016621.wp027.webpack.hosteurope.de/fotost/f01175/professionell_rds.jpg

Advantages of the Professional series (over the standard Business series)?
- Better sound quality
- Becker's trademark dual RDS tuner
- It's a Becker! ;)

If you'd like to get rid of the dated cassette deck, the Blaupunkt/BMW Business CD (CD43) may be another good option. It features much better audio quality than the old Business radio/cassette units and has an in-dash cd player. Disadvantages to the Becker Professional series: No dual RDS tuner and the trunk cd changer will no longer work (newer I-Bus vs older M-Bus). Nevertheless a very popular upgrade.

If you are looking for more modern features (like navigation and/or mp3 support) while still maintaining an OEM appearance, have a look at the Becker Traffic Pro, Grand Prix or Indianapolis series.

am I right in assuming it's in CSi's as standard? the M Audio I think

am I right in assuming it's in CSi's as standard? the M Audio I think

Come to think of it, I have seen it quite often in Euro spec CSi's. :shifty

am I right in assuming it's in CSi's as standard? the M Audio I thinkJud probably knows the correct answer, but since I've seen several 850CSi with the simple Business radio system, I doubt the Professional system was a standard option. I mean, who would replace the magnificent Becker/BMW Professional RDS or Becker/BMW Bavaria C Professional RDS with one of the much lesser units?