Good thinking mate. Took the car for a thrashing last night, it seems to have sorted it's running issues out + pulls alot harder than it has been of late + is holding boost fine, touch wood, at the mo. It hasn't recorded another overboost fault either. May try changing the DV anyhow for a Bailey re-circ as I've heard a strange whilstling noise a couple of times which mades me wonder if the standard vavle is leaking?