[jr_ss]

S13's have less than ideal valve cover vacuum setups. You could use that port where the metal plug is as an additional vac source, however most people just block it off. Adding vac sources on the VC are not unheard of and could benefit you. Some people use the PCV port as their additional source, but I like having vac at idle in my engine as well.

I run an exhaust scavenging setup for under boost conditions and the PCV for idle periods. I have two -10 male fittings welded to my VC and the factory PCV system.