For mic routing I strongly recommend what I did

Forget the visor. I have a Passat GLX and there is a nice seem in the dash just to the left of the steering wheel. I managed to push the jack through this and pull it out under in the area to the righ of the accelerator pedal. From there I ran it up under another portion of dash to the center console/ashtray area where the HFK sits. Totally invisible and I can use my visor. Instead of barking "wake up" at the roof, I bark it at my steering wheel.

Eric