Dunno, but you're welcome to try. The cost vs. benefit of it will be nothing more than giving you a random bragging right. Whoa'ing these boats down is decent with stock brakes, and happens pretty well in my GXP. You're basically going for an appearance mod that has minimal additional performance, biased to the front, and tempered by having less exotic rotor options than the original vehicle.
On that, if you do the research to see what standard C5/6's require to run C6Z brakes, you'll be able to combine that info with whatever people have done to put C5/6 setups on these cars... and if it's a viable option. If you're trying to get a quick answer from the few people left here, I doubt you'll find many non-routine upgrading going on (look at the content of average posts here vs. what used to get posted 10+yrs ago). More has been forgotten about modding these cars than what most people can hope to learn.
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