That noise is normal. It is the friction between the pad and the rotor. If it is a high shreak, check the thickness of your pads.

Otherwise it sounds normal. Once the pads and rotor come to temp, the noise should dissipate.

BTW Discs on all four corners, no rear drums. Except for the E-brake. It is a different component, not a part of the caliper system.

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2011 E70 50i M Sport