[C ///M]

Does anyone have actual piston specs for each of these brake kits? The one thing I'm very curious about is actually the rear calipers. Of course the calipers themselves will be different because they're both lug mount instead of radial mount, but I wonder if the F30 M-Sport rear calipers use larger larger pistons.

Then there's the front. Everyone says the E90 Performance/135i calipers are all show, no go; why is that? Are the 3 pairs of pistons all tiny? Does anyone know off-hand how large the master cylinder is in the 135 vs 328 or 335?

Thanks,