wastegate theory.

I’m new to Audi and to forums, I normally just Google my problem till I find an answer. I need help understanding the wastegate.
If a stock s4 pushes about 8psi and the wastegate are a failsafe and open at 9psi, how do people chip their car to 16 psi with no issue? Wouldn’t the car build boost till it matched the spring tension and manually open the wg? If people chip the car for 16psi shouldn’t they also adjust the wg to a different tension?

Sorry if this sounds kinda newbish, I tried searching and you guys seem a bit more logical that the rest of the Audi community.