If you fit an aftermarket stereo to a Mini with factory Navigation, you will
loose the voice.
There are 2 solutions; Fit a small speaker for the voice or use a navigation
interface as shown here
1. Remove ignition key. Disconnect your harness adaptor from the new stereo
(ISO connections)
2. Plug the navigation interface between the harness adaptor & the stereo.
3. Chop the Yellow/Red & Yellow Brown cables going to the white 12 pin plug
in the factory radio plug,
Connect the car side of these to the black & Black/Red
coming from the navigation interface.
4. The navigation voice will now interupt the front right speaker
5. If you wish for all speakers to mute when the voice speaks then connect
the trailing yellow/white wire to the mute wire on your new radio