This is almost word for word what airdam said in another post haweights dont create clunk in the clutch, the clunking comes from the secondary helix loading and unloading against the rollers. going from a dead stop to acceleration, or on decelleration back to acceleration, the helix can and will load / unload the face of the helix against the roller in the secondary. this is the clunking sound. the new machine has a new helix, the angles are slightly different, but this also isnt going to cause more or less clunking. some machines are better than others, some clunk a fair bit, some dont at all. there is a torsion spring in the secondary that is trying to put a load against the helix to always keep the helix pressed against the roller. in theory it works, sometimes you still get a little clunk. the new inner shield in the cover is for air flow and air velocity into and thru the clutch cover. if there is a noticable difference in sound, i would start looking towards the rest of the ducting, where its placed, whether or not there are additional vents or ducts or shields in this area. the outer cover "insert" does not effect the noise behind your head in the cab.