PLEASE HELP!

My Octy has got a noise when accelerating between 1800-2300 rpm. It only occurs when moving and not stationary. Two local specialists and a dealer (Silbury, Northumberland) and say it is an induction noise. Unfortunately none have suggested a cause or a cure. The air intake unit and pipe located on front grill, and air filter box have all been changed and still noise is there. The air pipes have been removed up to Air Flow meter and the under car engine cover have been removed to eliminate them, car, driven and again noise is still audible. It has been suggested the intercooler but the car certainly doesnt suffer lack of power, a bit of smoke under harsh acceleration but not under normal conditions. Clutch was recently changed to SMF not affected noise.