I must have missed it... How is it installled again? Definitely interested if it is a DIY.

 

You have to screw two holes into the diffuser part of the M5 bumper and use double-sided tape in the middle (for no gap).
Refer to this post for close up pictures of the installed diffuser --> https://5series.net/forums/topic/638...ost__p__804962

Here is a picture of where the screws are made:

 

Hi John, I sent you an email. Thanks!
-Gabe