If your car has Air suspension fitted in the rear, then you'll need to buy front lowering springs (common used springs are H&R or Eibach) and rear end links for the rear that trip the computer to keeping the car lower.

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" Despite its supercar attributes, the M5 still doubles as a soberly practical, spacious saloon - only with the ability to scare four passengers in comfort all the way to the local coronary unit". Top Gear