well I hooked up my boost guage and only to see that my evo 8 is only boosting 12psi.

Is this right?

 

I'm sure somebody can better explain but it looks like you're running at waste gate pressure. Have you installed an aftermarket boost controller? Where did you "T" into for the Gauge, was it by the fuel pressure regulator?

 

a vacuum line is probably off, as you are boosting only to wastegate pressure

 

looks like you bought a used evo and the original owner had a manual boost controller. before trading it in he/she removed the boost controller, and instead of replacing the stock vaccum lines, which have small brass pills in them, used normal vacuum lines. youll have to either get a mbc, ebc, or order the stock vaccum lines.

 

you got your lines croosed it sounds like but im no expert....