But there has to be venting for it to actually work as intended, which is why typically a 4 port will be used
in that method of plumbing a 3 port above, you would initially hold gate closed with pressure to build boost, then apply pressure under dome to control / lower boost, but there is still pressure trapped on the top so you are screwed .it won't exhaust anywhere because there is no exhaust port!
even if you didn't hold gate closed initially, once you put pressure under the diapraghm it will stay there when you swap to the top port, fighting you.
unless I am missing something here, which has been known to happen, it really needs to be a 4 (or 5) port valve to work
But really turbo smart do list other connection methods which are more typical. Would love to know if people have done it like above and what happened.