I think the piece youre having a hard time seeing is this;
on the 'cold side' of your turbo there is a little pipe. That pipe does not put air into your engine, rather, it is used to activate the wastegate. the wastegate has a little pressure sensing diaphragm that opens and closes a little door on the 'hot side' or 'exhaust side' of the turbo. Now, what this is doing is diverting the exhaust around past the 'hot side' fan blades thus tricking the turbo into boosting less. That wastegate door is opened and closed by the little pipe on the 'cold side' of the turbo acording to hyow much boost the turbo is making at the time.
example: (not technically accurate)
Turbo boost= 5psi ----> wastegate opens= 10% Turbo boost= 20psi ----> wastegate open=90%
All it does is prevent too mush boost for the situation.
SO, when you install a boost regulator what you are doing is putting something in-line between the 'cold side' and the wastegate tricking the wastgate into opening less, or more depending, than is would normally there by giving you MORE boost.Tricking the wastegate into opening less allows more of the exhaust to flow over the 'hot-side' fan (exhaust turbine) causing the whole turbo to make more boost.
makes sense?