Nice work on the brakes front. Performance friction definitely has a good reputation from my E36 M3 days, and I have no doubt they are making a good thing here as well.
Curious what the weight difference between the stockers, PF, and Z4 offerings are. If there is a decent reduction, between this, 17" BBS RGRs, and proper summers instead of run flats we are talking about a serious loss of unsprung weight. Anyone have a weight on the 128i M-Sport boat anchor wheels?
This also might prove to be a good fix for the brake heat limp mode that the 128i(at least we don't have the terrible 135i "BBK") runs into on the track.
*Edit*
Looked them up on
http://felgenkatalog.auto-treff.com/ It looks like they weigh 22.3lbs and 22.4lbs for the stock front and rears respectively. Stock run flats apparently weigh 26lbs.
Given that 17x8 RGRs weigh 17.24lbs and 235/45/17 Super Sports weigh 21lbs, we are talking about a 10.1lbs reduction in unsprung weight
per corner before brakes. That is an absurd performance boost.
