1.) How much power does your car make? around 250kw
2.) How much boost pressure do you run? 9psi on low 18psi on high
3.) What turbo? Hi-flow (unsure of specs)
4.) How big (in diameter) are your intercooler pipes? 2.5inch-3inch? full HKS cooler kit
5.) What do you seen if you take the plum back hose off and free rev the engine from the engine bay? Does the bov open and vent? Yes, even went for a drive like it, no reall flutter (did occassionally flutter just once)
6.) Have you tried to run a new length of hose Straight from bov to turbo intake pipe? nope, that'd be a long bit of hose, would have to buy a length of silicon tube or something to do that, an that stuff aint real cheap. but I see your point