These brakes fell in my lap right as I was about to pull the trigger a decent pad/rotor 330i setup for my 325xi, so I decided to make them work
Research online shows that you need to mill the m3 caliper bracket 6 or 7mm to fit non-M e46 cars. I went with 1/4" (mainly because my machine shop isn't fond of the metric system)
After the first test fit I had to go back to get him to clearance out some of the remaining adjacent areas to clear the mounting tabs on the spindles.
Once that is done, proceed with normal brake install and pressure bleed with your favorite fluid
note: m3 brakes use different set screws than non-ms hence the presence of lugnuts in this shot. Need to order 2 of those puppies up.
Brakes are still a bit squirmy as I haven't really had a good chance to bed them in thoroughly. Once I did get heat in them, however, they were amazing. Haven't had any spirited driving with them yet to see how far off brake bias is front to rear. -May DIY the rears here shortly.
Install should be the same for 323i 325i 325xi 328i 330i 330xi.