If youre wanting the big brakes, i would simply take the front knuckle right off, disconnect the brake caliper, abs /brake pad sensors, tension strut, lower contol arm, tie rod, and the axle, then lower the strut, and use that whole assembly, youll get a bigger wheel bearing, and all the brake stuff would fit! (need 18"+ wheels though)
Good luck!

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2003 X5 3.0i (02/2003) sport package, Sapphire black metallic / Black Dakota Sport seats. compass mirror retrofit, trailer hitch retrofit, Prodigy P2 trailer brake controller installed, PDC retrofit, Lumbar support retrofit. heated rear seats retrofitted. Running boards retrofitted and subwoofer install in progress. 4.8is Brakes installed front and back. Bluetooth TCU installed, Rear Fog lights installed. Retrofitted reclining rear seat backs.