wat acceptable boost 4 r32 gts4

hey, i was jus wonderin wat is a safe boost level on a r32
gts4, so that the ceramic turbo does not break or wreck?

i heard 12psi is dat true?

my r32 is a 1989 model does it make a differnce or not?

If you're cars air fuel ratio is good upto 14psi.