Guys, just a little warning - I tried 12mm all around on stock suspension and got rubbing on big compression bumps. It was rubbing at the rear, where the plastic bumper cover meets the metal fender.
Additionally, I was getting some weird little vibration transmitted at every sharp impact - could have been the spacers I used, who knows.
2004 Z4 3.0
2014 X1 28i ED
2015 F80 ED in June