You have to be careful about this, certain factory mics have different gain settings (I think, I'm not an expert) that can make them sound like crap with a non-factory bluetooth kit. I had this problem with my Audi A4, the stock mic sounded terrible and some guys on the audi board actually put together a circuit that could be wired inline with the stock mic so gain could be adjusted with aftermarket kits. I ended up just installing my Nokia mic in the stock location, ditching the stock mic all together.
So, I would just try it with the stock mic (if it has the correct connector, the one