I think that's a step backward.

With those rotors you have less swept area, less mass because they are smaller, and additional reduction in mass because they are cross drilled.

All things being equal they will reach threshold temps faster.

Just curious, in what situations do you feel the stock 4.6is brakes need improvement? I think they do a great job in anything I will ever need to do in the city or highway. I have not tracked one yet though.

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04 X5 3.0i auto
03 X5 4.6is