Heres a picture of the stock wastegate, that big thing connected to your turbo isn't the wastegate, just the wastegate actuator. That door is the actual wastegate which opens and closes via the WGA arm which is in turn controlled by boost pressure.
Thats an internal wastegate. An external one is the same but routes it to the atmosphere instead of back into the exhaust right before the o2.
Here it is from another angle, different turbofold but still the same thing
You can kind of see the hole in there which opens and closes via the WGA arm.
