I assume ur the guy who came and bought my STI bov off me a couple of weeks ago.

As the others have said, Any BOV that vents atmospherically is technically illegal, but i have heard of people getting permits for them. However, I think it, for some reason, depends on which pits you go to, and what mood the inspector is in.

Either:

a: put the sti one on, and leave it on

b: put the sti one on, go over the pits, change to back to the HKS one and just try not to vent too loudly around cops, or draw the cops attention

c: attempt to get a permit for ur HKS one?

good luck