Hi guys, I'm completely stumped.

I've just fitted a kinugawa waste gate to my stock 1996 850 T5 as I've been having trouble with boost dropping. The waste gate has come with a variety of springs, 0.3, 0.5, 0.8, 1.2 bar but I have no idea which ones I'm supposed to be using for a stock car. I currently have 0.5 bar fitted which boosts fine to start with but will not go above about 0.4 bar according to my gauge

Are the springs the upper limit boost I.e a 0.5 bar spring will only allow up to 0.5 bar of boost or have I got it set up wrong? I had a feeling the old Volvo ones were set with about 4 psi of preload pressure which is about 0.3 bar however my new one is set with barely any pressure at all as I figured the weighting of the springs took care of that?

Please help!
Thanks