There was a custom Rider3 navcore which supported MP3 playback (http://www.navitotal.com/showthread.php?5503-Rider3-app-on-non_Rider-and-old-Rider-devices&highlight=rider3) courtesy of bmwdriver. The link to download it however is dead. Does anyone have a copy of this or similar navcore they can upload?

(I couldn't post this in the linked thread as it is locked)