YAY new brakes! I had the car in this week for it's final check-up before the 3/36 bumper-to-bumper warranty expires (tomorrow) and got a few random things taken care of, a recall, and then the new brake setup. Chevy revised the Z51 rotors for 2017 and will replace the original 2014-16 bi-cast design with the new single piece cast rotors under warranty if they can measure lateral runout out of spec on the original set. I'm not sure what spec is, but they measured my fronts at 1.04mm and rears at 0.42mm which explains the high-speed pulsation.
Old:
New:
Yes, the revised design is 3 pounds heavier per corner, but after 32k miles I'm quite content with getting a new set of rotors for free. While they were in there, I also had them swap out the factory Ferodo pads for Powestop Z26 pads which should be quieter and dust quite a bit less (so far this seem true). Initial bite doesn't seem as good, but I'll let them heat cycle a few times and fully get bedded in before making too much judgment on them.