I've heard people on this board describe leaving the top port on their wastgate open to the atmosphere. What I don't understand is this: If you hook up the vacuum port on the wastegate after the throttle plate, it sees vacuum at idle but boost at WOT. Doesn't this tend to keep the wastegate closed? Do I need a check valve on the vacuum port of the wastgate to keep it from seeing boost or should I just leave it open to the atmosphere?

 

if no boost controller, then leave it open.

 

You only use it if you have an ebc.