Well, i replaced the diverter valve with a new revision OEM one and by god was it a hard job.
It should be simple but as there's no access to the valve from above, below or the side without contorting your body into totally unnatural positions. It took about 3 hours in total, that was about an hour per screw. They were tight from start to finish
Anyway, old verses new valves:
New on the left, old on the right.
And the damage to the old one that was causing the boost leak:
All sorted now and the car runs fine. The engine check light is also out now too