It does exactly what the original actuator does, no performance gain, its just if you want something shiney in your engine bay.

an actuator is something which operates something else, like this one in question under vacuum pressure it moves the arm on the variable vane turbo to move the vanes.
 
fair enough, but they do help out re-mapped petrols, why not diesel?

plus they state that they can place a strongger spring for higher boost levels?

i'm no expert tho.

ta