have an APS fmic fitted on 05 sti with hks d/v fitted on pipe running into throttle housing,have changed back to re-circ forge valve but getting lots of turbo chatter....is this right or should i unblock the intake pipe and connect the d/v where the bung was fitted???

 

For a re-circ valve to work it needs to be connected to the intake pipe.

 

Yeah as above. And the flutter is normal with a front mount.