Those are DEFINITELY Brembo calipers.
I'll even go to far as to say those are the same calipers used on the 2004-2008 CTS-V. With the script on the side, they even look like parts-bin CTS-V units.
4 piston front, 4-piston rear. The Challenger, Charger, Magnum and 300C SRT models use a similar arrangement.
I hope those brakes are not limited to just a top of the line SS model. I'd LOVE to option those out on a Z28.