BMW does indeed put a lot of R&D into brake performance and it is a signature for the brand in general. What are you trying to accomplish from going with non OEM parts? Cost savings? Improving some aspect of the brakes? Other than a track vehicle, which an X5 would never be - I don't see the reason to deviate from BMW's original design as relates to brakes. That's my personal view of course - YMMV.

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2003 4.6is - SOLD
2003 M5 Imola
2008 Mini Cooper S
2011 Mazda CX9