You are right that someone else with a C7 Z06 is best to hear from, but, every time I've been to a track my cars have given a different reading. Although the test should be held at a certain rpm, distance and angle from the exhaust, in reality these three factors change with human error (I can rarely hold exactly the right rpm for example!). Factor in weather, where the test is held (other cars and buildings surrounding), what rev limit you choose to volunteer(!), ambient noise, instrument quality and calibration and how warm the engine is and you'll find quite a variation.
My C6 with Flowmaster back boxes are usually around 97/98db static, but sound pretty quiet on drive by compared to many cars.
I had the pleasure of passenger rides in a C7 Z06 at Austin last year and whilst it sounded great in the car it was pretty quiet compared to most other cars from the grandstands.
This thread may help you:
C7 Z06 Track Mode Decibel level on Track Days - CorvetteForum - Chevrolet Corvette Forum Discussion
They are talking about drive by rather than static and Laguna Seca is particularly sensitive to noise.
In the UK your standard exhaust will be no good at some Croft or Bedford trackdays and you will never pass at Thruxton. My best guess is that you will be fine at all other normal trackdays, with Silverstone and sometime Donington being your best bet for a noisy car. Aside from the first three circuits I mentioned above I've not known anyone have a problem with any standard car with a dual mode exhaust, even angry sounding AMG C63. At Castle Combe last year they had a gorgeous sounding V10 Carrera GT flying round and that got under a 98db static test. My Caterham race car passed track day noise limits everywhere except Zolder, but that just required short shifting past the drive by noise meters.
Not sure if any of that helps, hope you get someone with a C7 Z06 to reply shortly.
