👍 ok forget my statement earlier.
it will fit as it is a performance upgrade to the 2SS. The 6 Pisten fit in all OEM 20” Wheels.
Extract from Performance catalog page 18
23245471
Brembo® Performance Front Brake Package (Six-Piston Calipers, Camaro LS/LT and SS)
Take the braking capability of your Camaro LS/LT or SS to a higher level with the Chevrolet Performance Brembo® front brake system, featuring six-piston monoblock aluminum calipers with performance brake
pads and two-piece, 14.6-inch x 1.3-inch (370mm x 34mm) vented
and slotted DuralifeTM rotors (cast-iron braking rings with aluminum hats). These performance brakes are for the serious track enthusiast looking for ultimate braking performance while maintaining street drivability – and they’re larger than the factory systems for LS/LT and SS (SS features 13.6-inch rotors/four-piston calipers from the factory). The DuralifeTM rotors feature a hardened surface to reduce corrosion and provide quieter braking with less vibration. This front-brake kit includes low-expansion front brake hoses, all necessary hardware and installation instructions.