So i'm getting ready to do the 6 piston brembo caliper upgrade on my 2007 Denali. I'm curious to know if there are any upgrades for the rear that would be a 4 piston upgrade. I did read somewhere that a CTS-V rear caliper was able to be used but i'm not finding any information on this subject. The only thing I found was a silverado 2 piston upgrade for the rear which are still the old caliper and bracket style setup. Any help or nudge in the right direction, is greatly appreciated!!