Does anyone have a D1 Spec boost gauge?

I am having trouble calibrating it to get it to read what the previous gauge read.I got it as close as possible and now it's reading 1 bar where the previous one read 1.2 bar.
It's got two small screws on inside the control motor,but i' can't get it to read accurately.

 

Not sure if anyone here has any experience with it. Never heard of it before. You might just want to try and sell it and get a boost gauge that is accurate and doesn't require calibration (like AEM, Prosport, STRI, etc).

 

I was looking to import from MAP but they're all marked in Psi and I need one marked in bar. Maybe I'll just try again to set it with the screws.