Can I put a Double Din head unit in a 2007 audi a4 with a stock single din head unit?

So my question is if its possible to put a DOUBLE DIN DVD navigation headunit, into my audi a4, which is a single din headunit.

NO
your car has a "Euro-DIN" and the stereos attach from the front through the 2" tall rectangular hole in the dash, sliding into a metal sleeve that attaches to the front of the dash.
and Double-DIN receivers fit in the 4" tall opening found in many Japanese and American vehicles.

http://www.crutchfield.com/S-xo29BFe3C5v/app/car/popups/ReceiverSizeCode.aspx

don't know your dash-board layout but you would have to go the custom route for that to work

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