Hi qsilver7
I do have settings "set" at the bottom and the volume control where nav sais "quieter". "Louder". However I believe this is different to the nav-min option

With the above the nav is just speak louder or quieter so if u have radio on loud she will just be quieter or louder over your loud radio

However the nav-min. Which u should be able to access from pressing "info" on the screen. Will control on a scale of -9 to +9
How much mute or no mute to put on. Radio/cd. When nav speakes
Eg -9 fully mute radio when she talk
0 would be just a half volume mute when talks and +9 would be no mute
At all on radio when she talks

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2005 E53 X5 post facelift