The 12mm mounts is why the CTS V V1 calipers are popular . No drilling and still available on Amazon. $137 rear, $192 front
I think these prices might be backwards.
2009 Liquid Red GT
Currently Enjoying : WeatherTech Floor Liners, Tein S. Tech Springs, Monroe PPV Shocks/Struts, SuperPro Polyelast Top Mounts, 19" Sport Wheels & Firehawk Indy 500 Tires, 18" GT Wheels & Continental DWS06 Tires, Subwoofer Wire Mod, Kayhan Audio Headunit, 35% Llumar Ceramic Tint, Morimoto 35W HID Kit
Soon to come: CTS-V 4 Piston Brembos, CTS-V2 Sedan Wheels