This is a red stoptech st-40 front and rear for a 46 m3. I was told the only difference between the m3 kit and z4m kit was the rear brake lines on the z4. I bought new brake lines which are included. The rotors have some wear, but I was using them for street use, so I was going to move the rears to the front to get more life out of them. The rotor measurements are:
30.94mm
30.84mm
30.46mm
30.48mm
Same size rotors so I was going to unbolt them and move them to the different hats. Anyway they have been sitting in my garage for a year, haven't had the chance to get to them. I also have spacers, to be able to use stock wheels for additional cost. There are some blemishes on the calipers, I can send pics if you send your email address. I was going to get them re-painted eventually. Price is $2500 plus 3% for paypal + actual shipping.