Originally Posted by johnbmw6
Mine is on the 330D M Sport, not sure if the upgrade is available to all F30/31 models, you will have to check. Anyone?.
US 335i's come with the M Sport front brakes as standard, well same calipers, not sure what disc size they use.
Here in the UK, the M Sport brake upgrade gives the 4 pot calipers painted blue, with bigger discs all round. I can't remember if the rear calipers are 2 piston or the standard single sided piston but are also painted blue.
It is basically the same caliper kit as M Performance but with non drilled discs. Which to me is a bonus, having drilled discs on anything other than a track car is stupid.