<<Knowing that the Z06 was specifically designed for the enthusiast, I would be very suspect of any upgrades that add significant value to the car itself. >>
Ben, I'm not sure that I understand your statement here. Are you saying that you'd be suspect of a mod that's supposed to make the car better, 'cause if it were true then GM would have made the car that wy to begin with? What do you mean by "add value" to the car?
If I have your concern correct, then I'd suggest that the Z06 is STILL a "mass production" car, and GM (and all car makers appealing to a large market) is forced to find a balance between cost, performance, and driveability. The car has to be amiable to the "average" buyer, and not just be fast (for the speed enthusiasts). So, is the car going to be as good (read: fast and efficeint) as it can be with aftermarket add-ons? No way. Did the GM engineers do a decent job of finding the balance I noted here? Sure. Again, there's almost always room for improvement, though.
Take the air box, for instance. I just put a Donaldson filter on my car last night. Upon taking out the factory airbox (you remove the whole unit with most aftermarket intake set-ups), I got to see just how restrictive the stock unit is. It's downright ABSURD. Now, why is it like that from the factory? Looking at the design, I really don't know (it's THAT resptrictive). But maybe GM "had" to make it that way. Maybe increased breathing changes the fuel ratio, and maybe that would have hurt the exemption that the CAGS seeks to gain. And maybe more airflow would have required a more expensive airfilter... There seems to be a trickle-down effect with some of the reasons for the engineering on these and most cars -- and maybe GM couldn't have "afforded" to do this intake another way, even though the car would RUN better if they had.