I'm happy enough with the stock audio head unit in my 2003, but I've always wished it had an AUX input for an MP3 player, etc. Here's a thread I started on an electronics forum which lays out how to do an internal mod to the player to add an external AUX jack. Probably not for those with little electronics experience, and especially with no skills/tools for REALLY tight soldering: http://www.electronicspoint.com/thre...stereo.269439/

The post includes schematics/foil pattern images of the mods, as well as links to the full service manual for the stock radio, which I've posted.

Dan