Good write up, good mod, looks cheap but useful. I can see there's only two spare pins on the mirror plug so that's clear which to use for the new wires but you don't give any guide as to which pin/sockets to use in the door plug and socket. I guess for the door plug and socket any pins/sockets which are unused on car and door side will do but it would be nice to follow VWs convention. Also do you have to connect a particular wire from the mirror plug to a particular socket on the mirror glass plug or is whatever makes it darken not sensitive to polarity? Finally can you give a rough idea of the costs of the two mirror glasses? I'm guessing the reminder, crimps, plugs etc is a few quid.