Hi all, after a poor performance on a recent trackday im doing the “easy” brake upgrade, ive sourced the front calipers from a 3.0si and the rears from a 320d, my question is does anyone know if i have to use the z4 3.0si discs or can i use the e46 330 front and 320d rear discs as there seems to be more available and at better prices if you say e46 even though the disc specs look exactly the same? Thanks