The above quote sad to say is wrong, i think you will find a standard car will pull the flap right down, which is why the hydro electric pressure actuator is adjusted, but usually with compromised fuelling lower down (running a bit rich)

Why do you think EFI cars need a 3bar map sensor when you go above 15psi of boost??????

And of course not everyone on here takes their car to the tuners to have their boost adjusted slightly, but those who do don't run the risk. If your going to tell people to double the boost they're are currently running at the very least u need the alleged "spanner and boost gauge" aswell as a good Air/Fuel ratio meter.