I just pulled this off the f30 FAQ from here:
What are the brakes on the F30?
The 328i has single piston floating calipers on all four wheels. 335i gets upgraded to 4 piston fixed caliper up front and single piston floating caliper in the rear. For complete brakes specs see the F30 Complete Specifications thread.
However, when searching the specification thread it doesn't mention anything else about the brakes other than rotor size.