Hi all, Ive got the F500bt portable, which i think is brilliant.
My only complaint is that altough the system mutes your music etc to tell you the directions, when I come to a speed camera, only the head unit seems to make a low volume bleep or whine and visually show you. The amp doesnt seem to put it through the car speakers and it does not mute anything to let you hear them, meaning if you have any kind of volume to your music, you can easily miss the camera alerts.
Is this a common problem? or does someone know how to fix this? 
Any help would be appreciated. Thanks