i've had vta dv on both my clssic imprezas. boths types of bailey and a greedy one. i've not experienced any problems whilst having them on there, but they do cause a slight overfuelling.
fitting an induction kit will allow you to hear the turbo stall / wastegate chatter. but the ik can cause the maf to die.
either way you'll upset the car slightly. if you've got a mappable ecu fit both and have it mapped accordingly.