Below is the rotor and pads used with the stock G54 vs the G60 brakes. The outside diameter of the rotors is almost exactly the same, but the size of the pad is bigger with the G60 setup.

Here are the G60 brakes. These were already an upgrade, but not enough.

The Porsche calipers and 2 piece rotors give better stopping power and are lighter than the stock and G60 brakes.