the z4m and e46 CSL share the exact same breaking system, even down to the caliper bolts so, this kit should fit the z4m perfectly!! Its expensive though, the 6Pot APs look lovely, before i do anythink im going to run some extreme pads, Race fluid and braided lines, i no this setup will be no-where near your stoptech's but ive been told the stock breaking system is actually very good, it just needs tweeks, then again the stock breaking system was never designed to contain my power output, but its worth a try!! i dont get how k-sport can offer front and rear 6pot kits for UNDER 1000!!!! how the hell is that possible? they get great reviews on different forums also!