Just found out from my VW Service Manager that he checked with VW Tech Support for update software for the new retrofit MDI I had installed. Apparently an update exists, HOWEVER the software update does not work on the MDI retrofit model (part #5N0-057-342). The update only works on MDI's that came installed at the factory as part of the package with the RNS 315 and the sun roof! Does this mean that the retrofit MDI I installed is already updated or is it just more bad news for those of us who are trying to add in a retrofit VW MDI to work with a retrofit RNS 315 Nav unit??? The fun never stops.