ok here goes
if around 100 kpa is 0 vacumn and boost ,
then anything under 100 is vacumn , but if you convert it to psi it says 14.5 psi, which i think is 14.5 which is equal to atmopsheric pressure
so if 158 kpa=22.916 psi then in order to get the correct psi above atmospheric pressure you have to subtract 14.5 from 22.916 which gives you 15.4 psi
so 158kpa is 15.4 psi in the f.a.s.t. tables
am i right ? let me know guys
thanks