I have an intense interest in curing this fluttering issue before auto X season kicks in, as it is going to be a little awkward having a car that chirps like a giant bird whilst dodging cones.

I know it isn't the BOV itself either, as I've tried an SSQV and a TiAl, both same results.

Anyway, there has to be a means to a cure, and one of my theories was kinda hinging on the mechanics of the engine itself.

So there is always at least one cylinder filling (creating vacuum in IM), right? So what is happening at part throttle/in boost (hits ~20lbs) that is causing this oscillation? And why would using a vacuum regulator not work? In theory the regulator would work by not allowing vacuum to hit the BOV unless it reached a certain level, i.e. 14inhg, right? This value would have to be tested of course, but as long as the oscillations never reached that value, the pressure differences from them would not reach the BOV, but when you let off the throttle, the IM would drop to 20inhg or so (mine does, if I remember correctly), opening the regulator and then the BOV, venting the charge.