It is not supposed to be a CA standard database. It clearly states at the bottom it is for comparison purposes only. Its purpose is to give people an idea how loud one system is relative to another, not what would keep you from getting a ticket.
The database is very valid because it is done with the same equipment and the same standards every time.
Unabomber, don't forget to look us up when you are here this summer. WRX03 claims to have the quietest stage II anywhere, we want to prove it.