Aftermarket systems like the dynavin come with a separate GPS antenna module, so year model is irrelevant.

OP, I have had success with mounting them to a metal part of a the from in the dash support. You just want it sitting up as close to the underside of the dash skin as possible. Perhaps pull the upper vents out, feed it back up I'm there and a bit of double sided body mould tape will stop it dislodging and rattling.

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2005 3.0d Sport - Sapphire Black
Engine : Bluefin Superchip Tune,
Wheels & Sus: Style 168s (10.5s all round), H&R RDA Spacers, Bilstein B12, Eibach 40mm drop, Whiteline RSB
Exterior: Le Mans flares, 4.6is kit F&R
Interior: Dynavin N6, Blackvue DR650 dash cams

My Build Thread: http://www.xoutpost.com/bmw-sav-foru...run-sheet.html