Just wanted to say a quick word about the standard head units in the e46's. Mine worked OK but I killed the CD auto changer. Oops. Anyway I spent ages trolling the interflop and made a aux patch lead only to find it didn't work with my business head unit even though it already had a aux socket spare. So I went to my local ice dealer and brought a nice little Kenwood head unit with USB, aux & sdcard inputs built in. Needed a couple of adapter harnesses to convert the Kenwood to BMW loom and another for the steering wheel controls. You'll need a radio plug adapter and a facial plate too. I brought the facia plate from Halfrauds. Cost £180 total and took 10 minutes to fit literally! Just had to cut the plastic strap at the back of the stereo mounting hole away so the new deeper head unit would fit and voila jobs a good un! Brought a 32gig sdcard and fitted my entire MP3 collection on it. It even does searches and works with iPod playlists if you own such a beast. Saves all that monkeying about with old Philips head unit.