It's depending on which knuckles you are using. But for the 2wd cosworth knuckles you can get adapters to use the 4 pot Brembo calipers off a BMW E38 728i with 324 mm Focus RS mk1 discs.


But of course it all depends on how much room there is inside your wheels. I made my own kit using 4 pot Brembo calipers off a Mercedes S Class and 356 mm discs.