awx strange boost noise under 2k rpm

[adamb180]

i have a strange little problem, under 2000 rpm i get a loud boost noise almost like a leak, there is no loss of power when this happens, as soon as the car reaches 2k rpm it disappears and goes completely silent, it also pulls slightly harder. I have checked all pipe connections and all pipes for splits and tears and there is none, i have cleaned out the egr and inlet manifold and it helped slightly but not much. it sounds like its coming from the area around the egr valve. Any help would be appriciated