I installed the brass bushings at all 4 corners. Not thrilled with the quality of the Bimmerworld pins, the hex was really poorly broached and not very deep either. I was able to get it to torque up but can see it stripping if I'm not careful. Also had to grind the inside of the front calipers with a small flap wheel to make room for the c-clip to seat fully. Not sure why they don't just make the bushing a hair longer.
The bushings don't seem to make a huge difference...we'll see how they feel on track.