So I was looking for a good place to place my Valentine one, and I tried a lot of things - I really wanted a stealth install. I tried the headrest in the back, but I could not get it to fit inside as on my S55 it is a bit tight in there.
So I finally decided to just mount it on the passenger visor with the V1 visor clip, and put the concealed display in the ash tray. It works out well, I get good signal because it's high in the windshield and not blocked. I have to take it out of the car overnight as I don't want it stolen, but it's OK. I will keep it like this now, but I really wanted a completely hidden look so I don't have to take it out of the car. The CD can stay in the ash tray as it closes.