I have an '85 535i and tend to drive it rather hard. After warping the front brakes twice on the same road, I upgraded the front brakes to the 4-pot units out of the m5 and the car stopped beautifully, but dove considerably. I then upgraded the rears to the vented brakes off the e34 540, and couldn't be happier with the results. It stops so well now that it HURTS!