The correct position is passenger side, inbetween the dashboard and headlining (the angle I took the photo makes it look out but its perfect - The distance between the top and bottom of it is the same(I'm such a saddo I measured it!)). I've seen very bad installs of these done by VW dealerships some install them horizontally at the top of the windscreen as well!!! (Followed by the GPS aerial stuck on the dash
!!!)
Here's mine when I fitted the DNX525DAB...
Nice and tidy, correct height, no cable showing, also the earth strip is stuck to the metal under the A Pillar...
No offence but the install in the post above is a right old dogs dinner! Upside down on the wrong side of the car, installed too far from A Pillar so no earth strip is making contact with metal and showing the cable and also the potential for the windscreen wipers to affect the signal when they wipe across it when on!!!