Does anyone know how to read the stock boost gauge?

or how to convert it to PSI?

the owner before when i bought it put in a boost controller
and i think its way to high and hitting fuel cut becuase its really jerky under boost

and i just want to know in what range i should be getting on the stock boost gauge


like right now when i get on it hard the gauge goes up around 3/4th of the gauge

and i know thats not good

 

Break down and buy a real gauge, I would almost place money you are hitting fuel cut because you don't have a FCD if it is hitting 3/4 gauge (at least mine won't)