had the same problem with my 32 stock turbo, when its on (idle will do) get a pair of pliers and pull the actuator arm to the front of the turbo, if it stops or noticeably makes a difference then your actuator is getting lazy, you can either buy a new one, a second hand one (r32 or 33, though 32 will make it run 10psi thereabouts) or buy a new turbo and what not but that really isnt needed. no big deal, just doesnt sound nice and might effect the way it builds boost if it is bad enough.