[tylerhart_21]

Looking online and doing some research, I have found out that the e9x 335i uses the same piston as the e9x 328i (57mm). But they use a different rotor and pad size. In addition the e9x m3 uses a 60 mm piston (Key note). On the e60 brake caliper (any non-m) they use a 60 mm piston and a 30 mm (pad I believe). The numbers on the caliper are 60/30/X. The bigger piston is within the 3.17 mm limit that is suggested and is based on the Alpinas where they give the b3 the same calipers as the 5 series. Plus the difference you would be getting is the braking/clamping force. My question is would doing down the e60 brake caliper route would be the best?

[TGTIW]

It's all about a balance of the specs involved and deciding what gives you the best results. So yeah, the 328 and 335 piston is the same size, with the 335 pad being slightly larger and the rotor being larger in diameter and width, which gives you better braking leverage and heat dissipation, but of course more weight.
The e60 calipers have a larger piston, which will give you a greater clamping force but a slightly softer pedal (enough to be noticeable, I don't know) and you get the same benefits and negatives as the 335 rotors.
Another option to consider and the one I went with. 330i rotors and caliper bracket. You can use your 328 caliper and pads, and the 330i rotor is 330x24

So going with the 335 or e60 option, is the additional braking performance worth the weight? I'm inclined to say no, only because I feel the 335 and e60 calipers are oversized for the pistons and pads they carry.