3sgte back in again after solving oil leak (oil cooler seals) as well as investigating low boost. Turns out the old actuator was leaking (which should increase boost) but the hole in the arm was now elongated so I think there was not enough/any preload to keep the flapper gate closed. So bought an aftermarket actuator with 11psi spring. Disconnected the factory bleed TVSV system, so there is just the spring and wastegate controlling boost and some preload via the adjustable arm.
Previously the car would occasionally see about 9psi, but son was saying that by the end of the Wakefield straight he only had 6psi. Now it spools fast and straight up to fuel cut (approx 12 psi) within a few secs - a different car. Need to fit a voltage divider to raise the fuelcut - I'm thinking 15psi. My target boost is say 13.5 to 14.5 psi but don't want any momentary spike to hit the cut. It will be a bit of trial and error.
Anyway when driving, at different times there is this occasional HOOM sound for maybe 1/4sec, as though something is resonating a body panel momentarily, but I'm wondering if it it the sound of the blow-off going back into the intake piping. It sounds like wind blowing over an open pipe. I haven't heard it before and it does not require big boost. Anyone recognise that symtom. I was able to recreate it with the throttle pedal at one stage, slight on/off the pedal...made me think of the BOV...??