New BMW radio/CD player for 2005 Z4

My dealer tells me that there is NO WAY to upgrade the OEM radio/DC unit on my Z4 because BMW "wires" each radio to each car.

This sounds like pure bullsh--. An aftermarket guy tells me he can replace the OEM radio with an aftermarket unit.

Does anyone in the club really know about updrading to a newer version of the OEM radio/CD - say one put in a 2009 Z4?

I'm new to BMWs and have found that many things make no sense - unless you want to drive fast. .

Thanks

Check out http://www.europeanautosource.com/ - they have updated / upgraded factory BMW radios you can use to do a direct swap out.