Whilst trying to work out why boost was dropping off above 4.5k i checked through various pages on here and read through the manual a bit. The Pierburg valve kept cropping up and how it might cause similar affects so i though I'd have a look at it. Well ive been looking for about an hour now and come to the conclusion that it's not there?

Am i right in thinking that they're usually mounted to the slam panel?

On my car the pipe comes from the bottom of the turbo, into a bleed valve (not fitted by me) and then straight into the actuator. The Pierburg should be plumbed in there somewhere right?

Would the lack of this valve cause my boost to drop off? It boosts up to just under a bar and then tails off at 4.5k to about 0.6 / 0.7 bar (due to the location of my gauge its really hard to look whilst not crashing).

I know people remove these valves but why? If you want more boost can you not fit a bleed valve into the system in the same way it does without the valve?

So many questions......