Well my new M3 rear bumper arrived today, so without any holdup it went on immediately, the mark on the corner is my mucky hands, as before it arrived I was in the engine bay removing the compressor for the air con.
All I need to do is fit on the side skirts now ( I also got some side skirts with this bumper, actually 2 sets one set is M3, the other is standard) to put these on I need to drill the sills, I think this will be done after the roll cage is fitted.
Here are another 2 photos of the car as it stands at present.