I have a HKS SQV vent to atmosphere dump valve fitted on my 1992 MY93 import, and it has a bolt on the back of it with 2 nuts.
At the weekend I loosened one nut so that I could tighten the other.
What this has done is push a plate inside the dump valve slightly forwards towards the actual vent. Basically the plate has a spring on there so it is now slightly more compression within the dump valve.
Whilst driving it, it now seems as though I don't get as mush boost throughout the revs, I get full boost at about 3 - 3500rpm of about 1 bar, but then it drops rapidly to maybe 5 - 7 psi.
I am going to undo the changes so hopefully my boost won't tail of so rapidly but does anyone know an explanation for why this happens.

I actually did it as I thought that with the spring being compressed more, it would help keep the boost longer. but could it be that by compressing the spring, the boost is going back to the turbo and stalling it?

 

Adjusted the valve back again and I am now suffering from hesitation occasionally at approx 4000 rpm. Possible some kind of faulty seal on the dump valve thats letting air out when it shouldnt, thus resulting in a loss of boost
Think it is time to get a standard recirc on there I think.