I just did the Z23's on my car and love them, as the dust is gone!!! Break in is easy. 5 aggressive stops from 40-10 without letting them cool, then 5 moderate stops from 35-5 again without letting them cool, then just drive it as long as you can without touching the brakes for the cool down period. Got a few weird looks in my neighborhood as I would rapidly accelerate, then cram on the brakes many times in a row. Oh well, don't care what they think. Now my brass monkeys, will stay brass colored!!! Oh and FYI the first few stops it will feel like they are not really there, but they bite in quick after that.