I'm definately not underestimating the driver's role. And I completely agree that it is "usually" the middle of the pack guys that are cheating. I can give you a list of Spec Miata guys that cheat and what they are doing to cheat. Most of them are middle runners, but not all.
I was just wondering how this particular piece of the puzzle is monitored. On a BSP or SM EVO 30hp might not mean a whole lot, but in STU where the cars weigh quite a bit more, are on street tires, and you are only talking 290-310whp anyway 30hp from more boost is a definate advantage. If it can't be monitored, I'd be willing to bet most guys are running increased boost...even if they don't know it. You take your car in for a tune and say make more power, the tuner might get a couple psi out of it on 93 octane and you never know it.