The Brembo brakes included in the SL-C kit are based on the 5th gen Camaro SS brakes. These calipers have OEM-quality dust seals, are relatively lightweight, and because they are sized for a car that weighs over 4000 lbs, are more than adequate for a lightweight car like the SL-C. Interestingly, these same calipers are provided to other OEMs on very high-end cars as well.
The front brake package includes Brembo-sourced 355 mm (13.98") diameter x 32 mm (about 1.25") thick vented rotors with four-piston aluminum calipers. The rear brakes are vented Brembos measuring 365 mm (14.37") in diameter x 28 mm (1.1") thick, with aluminum four-piston calipers. Note that in a reversal of common practice, the rear rotors are actually somewhat larger in diameter than the fronts.
Using the brakes from a production car like the Camaro SS means that there will be spare parts from a wide variety of sources, resulting in low prices. It is also likely that the aftermarket for the popular 5th Gen Camaro SS will be a source of 2-piece rotors, different pad compounds, etc.
There are plenty of options in terms of drilled and slotted rotors. And substantial weight savings can be obtained from 2-piece rotors.
The Brembo calipers have a wide range of pads available for different purposes.