Post note; the original gauge in the dash reaches only half way and not 3/4 on full boost.
The gauge I've just plumbed in is a Stack and cost me £60.
Yes I've suspected the actuator being weak and / or creeping open, but I didn't expect just 5 psi on full chat.
Being a lazy sod, I was intending to fit a boost control valve set to open 10 psi which means it doesn't matter if the actuator is weak or not. But I suppose replacing the actuator is the correct solution.
