Highly recommend the Jabra BT SP 700 visor-mounted speaker phone. 5 minutes after buying my Pre, I was leaving the parking lot listening to Pandora music being broadcast to my FM stereo via this Bluetooth unit while receiving turn-by-turn instructions via my stereo (and Pre) at the SAME TIME.

The Pre would slightly mute the music when a turn came up so that the Nav lady could tell me to turn and then keep on playing. What a wonderful experience.

Your experience may very depending on your FM attenna (my Cadillac CTS has an embedded antenna that makes it work VERY well) but try it out...if it works, it's much more useful than just a head piece and call quality is excellent.