Switching actuator
 

Ridddle me this - my switching actuator's intermediate lever-arm came off the other day, leaving that flap in the exhaust manifold that (i think;) flips down to cover 1/2 of the turbo inlet free swinging.
so... now im getting much higher boost levels (according to my idiot guage in the dash, i still havent hooked up an accurate guage) much more quickly than i did before, and i hear a pleasent tap as the door switches from vacuum to boost: *click* *psshhheeeewwwhiirrrrrrrrr*

so what i need to know is: what does the switching actuator do exactly, why was it engineered into the car to begin with, and how does it limit boost by closing off one of the turbo exhaust side inlet holes? is it simply the restricion that the valve delivers at high pressure that limits the boost levels?

no

LOL! It's part of the wastegate. You want to fix that. Unless you want to keep going with uncontrolled boost.

i have blown up 2 turbo motors by negligence with high boost levels - but it isnt above 40mmHG on the idiot guage - and im not experiencing a fuel cut. plus it has nothing to do with the wastegate, its the twin scroll valve that is supposed to provide more backpressure and a sharper boost curve at low rpm...
i think i like it though, and im careful with the throttle, never boost for long duration, and my car runs COLD as ice. i have straight pipes all cats removed and clear intake+tid, so maybe i can boost fast withought the twin scroll system :p:

The spring that holds our wastegates closed is in the actuator housing, so if it's unhooked, the WG is hanging wide open, which reduces boost and causes slow spooling. I left mine unhooked on purpose for break-in. Or are you talking about the twin scroll dealie? I have an S5 so I am ignorant on those.