For what I know MAP sensors are very common with turbo cars. Dunno about modern stock cars, but ie. Cossies use MAP sensor and usually when tuning turbo engine with aftermarket ECU, a MAP sensor is very common. IE. my current N/A Pinto engine has stock ECU with MAF, but if I'm going some day to different ECU (Megasquirt) and turbo I'm getting rid of the MAF and going to use MAP instead. I'm not even sure if common aftermarket ECUs are able to read MAF sensors properly.
the actuator controls the boost by operating the wastegate they both need each other to work without a actuator the waste gate wouldnt know when to open.
or in terms of a aftermarket controler its then controled by this but as allways their is actuator in most electronic boost controlers.
the actuator is something that regulate's the boost pressure and once the pre defined pressure is reached it will allow the excess pressure to open the gate. this is how it works with internaly gated turbo's and a boost controler will do the same thing to the air befor it reach's the actuator to keep intake pressure's at what they have been set for. allso internaly gated turbo's actuators can sometimes be adjusted with a small screw.
im not up to speed on extrenaly gated wastegates but in due time ill learn more about them
yer i noticed that i went through 3 manual boost controlers untill i found one that spike's less then 1psi what a bargen for 15$ off ebay my brother use's a AVCR to controle boost and my 15$ one dose the job for now.
Yeah I actually tried to be more exact but my English writing skills didn't allow that. Tho I was only trying to explain the wastegate's side of things so thanks for proper explanation in readable language.