So ive had a ton of boosted setups over the years, and never had this plugged, but i was doin some pressure testing and found that this port will allow boost to exit the setup, but its before the throttle plate. My buddies car was running like complete dick and had that capped and we took that off and it ran better for some reason, so should it be plugged or not?

 

i welded mine shut..

 

it needs to be plugged, otherwise, under boost, you have a leak, on an NA setup its fine beacuse its before the TB

 

heavy rubber vacuum cap with zip tie.