Hi Petes da
Need to bypass the solenoid the now to get the car to produce a bit more than 0.5 bar of whoosh
The map contained in the Z4 used to control the boost will be for a TD05 turbo and not a VF series but i think if all was well this would give overboost and not std actuator boost of half a bar.
Make sure the solenoid on the wing is working fine, unbolt it and turn it upside down, connect the green connectors under the dash together and spray brake cleaner throough the solenoid. If it is working fine then it will be clicking away with the green connectors together and the ignition in the on position. If the solenoid is not clicking then the solenoid if goofed and this will be the reason you are getting only actuator boost of 0.5bar
As the map in the ECU is wrong for the turbo you have fitted, we need to control the boost by other means. Fit a Manual Boost Controller from the actuator to the turbp pressure output nipple. Slowly increase the boost controller and get the boost to sit level at 0.8bar. Target boost for the Z4 is around 0.9bar but if you aim for 0.8 at the mo then the fuelling should be fine. Later on with access to a wideband afr meter and det cans you increase the boost to a level dictated by the wideband afr meter and the det cans.
I am up around your way on Sunday, funnily enough the exact same place as i last looked at your car. If you still have my number then give us a phone on Saturday