right then , can somebody explain to me how my hks evc3 is supposed to contol its boost?

my old amal valve had one pipe to compressor, one pipe to wastegate and the last pipe venting to atmosphere , which i can totally understand.

but my hks has a pipe to wastegate , a pipe to compressor and the last pipe to the inlet after the throttle plate??

just wondering how its bleeding air off when the last pipe is on the inlet, surely it is seeing pressure here too??