I've had my F90BT for about a week now, and I was jotting down some of my general questions this morning on my way into work...

1. What is the ATT setting do for GPS sound?

2. Is RDS a hardware feature or could they unlock this somehow through software? (Maybe it's up to the mod/hack section to figure this out if it's software...)

ATT stands for Attenuate, it lowers the music during voice guidance rather than muting. The RDS question can be answered by another member.