Just thought I'd add, if you're tying to improve sound..
This is my Kenwood KIV-700 (same thing as the BT900 minus the bluetooth):
It brought my OEM non-hk speakers to life using the built in preamp. The sound was so improved in fact, that I sold my 4-channel Alpine amp. So many options in this little thing.. For example, I can the distance that each speaker sits from me in inches, has built-in crossovers, speaker size select, too many to list. Also color matches my interior lighting perfectly and plays video. This is an iPod deck BTW, so no CD playing capabilities whatsoever.
For GPS, its hard to beat Google Navi on my Android phone + a windshield mount.