I would have thought that it would of been plugged and the boost controlled solely by the actuator (it would have to be an uprated one) or the free end would be partially plugged to vent some pressure like a manual bleed valve. If the pipe was unrestricted then I suspect the car would be overboosting due to too much bleed off (but I could be wrong, maybe the bore isn't big enough or the actuator is wound right down).