http://www.turnermotorsport.com/t-br...fferences.aspx
This link a good breakdown of all the different brake system and options BMW has been so confusing about with their lack of clear options (more so '12-'13 years). There is another link for 335i/xi.
But also according to Turner Motorsport you can just throw in the StopTech pads into your existing M or M Performance 4-piston brake calipers if you feel the M Performance pads lack feel or are spongey.