Issue 1: I can hear exhaust pulses (exhaust leak?) through my ACV, despite the fact that I've got the check valve in place... it seemed to be in working condition though.

The question being why...

Issue 2: The ACV is sucking air in with the pump off... it shouldn't be (unless you give it heavy throttle and let go immediately, do to the anti afterburn valve).

If it's sucking air, it must being going into the intake... this must be causing a vacuum leak... since it's not going anywhere else (except maybe the split air hose?... but that doesn't make sense as it's not a vacuum source).

What could cause this?