Believe that GM, knowing when they created the StingRay's digital instrument panel (IP), that the 2015 Z06's were going to have/need a boost gauge, that the boost gauge is "virtually present" in every StingRay, requiring only a software upgrade.
Whether GM would allow such IP upgrade to cars coming from the factory without a supercharger is the difficult question. Perhaps if you sign an acknowledgement of "partial warranty voiding," and pay a fee, they might allow that. Or, just like aftermarket tuners have figured out how to eliminate the "skip shift" feature in their programming updates, maybe such folks would be able to bring the hidden boost gauge "out of the closet," have it appear as one of your StingRay pocket gauges. Remember posting this picture on our forum about eight months ago.