I brought this up before, but this time I went ahead and did it. I bought both left and right side door airbags from a 1998 M3. They look perfect, only $30.00 for the pair.. All I need now is to either buy the knockout door panels, or custom mine.
Sure, I could do without them, but I love having a "To Do" list. Otherwise I get bored.
Looking at the pic of my door, I imagine it goes over the vapor barrier. Can you see the yellow connector, it's plug and play.