I've done what you are searching on my non m.
Bought the calipers, brackets and brake lines from rallyroad. The owner Eric Coulier is a great guy and will crarify any doubt that you have.
For the front i use 996 calipers (996 351 425 & 426), M3 CSL rotors (345x28) and brackets for non m.
I haven't gone for the rear yet but you need 996 rear calipers (996 351 421 and 422) and m3 e46 rear discs, the bracket is the same that the e36 rear one (Eric told me that).
that if you have a 330, but if you have a 325 let's say you need also the complete brake setup of a 330 or m3 or you will loose the hand brake.
The inner diameter of a m3 disc is simmilar to a 330 wich are bigger than the rest of the e46 family 328, 325 and so on.
Last edited by cuprafenix; 12-23-2012 at 08:27 PM.