I will be buying a Sonata SE turbo soon and am trying to decide if it's worth it to spend the extra $ for the nav system and upgraded stereo. I already have a Garmin GPS and don't especially need the in dash nav system but I'm a big music listener and would hate to be stuck with the base factory stereo if it's not decent. So for those that have the base factory stereo, how is the sound quality? For those that have the nav system and upgraded stereo, do you think this system is worth purchasing just for the sound quality of the stereo? Any thoughts, or opinions would be most appreciated.