maybe just try swapping them, you shouldn't need 2 bov's just to get rid of surge.
if the compressor blades were to come apart which is not very likely in the short run it could damage the motor.
the worse thing is that you are slowing down your turbo between shifts, when the bov is working correctly, you loose the pressure in the charge piping, but the air velocity/speed of compressor wheel stays mostly the same so you hit spool quick again.
surge you are hearing is the pressure trying to escape back through the turbo, which slows it down and can have ill affects on the bearings over time, when your compressor starts to wobble too much, the not very likely stuff breaking becomes more likely in the long run.

 

swapping them? like my fake hks for my real one? but if having 2 bovs is just overkill insurance that would be fine by me. I read a few people did this and it rid them of the pigeon surge
Well i dont think my turbo is slowing down between shifts(im auto), i hear no problem on accelerating or shifting only when i let off the gas it makes this noise.

I moved around the vacuum on the bov a couple places and nothing, anyone ever install a screen on their turbo for engine insurance? i imagine a piece would have to go thru al the intercooler piping to hurt the engine but still