Here's my thoughts on it...
Take the boost gauge line from the intake manifold because that's exactly what the engine see's, and that's what you are aiming for when tuning the boost.
Where the actuator vac line comes from, (in my car I have a high pressure actuator and with a direct vac line between the cold intercooler pipe and actuator I'm seeing 18psi+ at the intake) This is not what i want.
I don't have a nipple on the hot side but i would rather take it from there, so if there is a couple psi drop over the intercooler i will have the WG opening a couple psi earlier, thus giving me a lower manifold pressure with out using boost control.
I know i could just use a 1bar actuator but i want the actuator to hold set pressure till redline.
Correct me if I'm wrong here, but the lower setting actuator needs less exhaust manifold pressure to force the WG open while the actuator is trying to keep the WG closed, thus giving boost drop.