I had a maddening clunk in my TT for several months after I had installed new coilovers and a camber kit. After swapping struts and camber kit components from side-to-side I almost gave up my quest to find the source of the clunk. The strange thing about this particular clunk was that I only heard it during forward acceleration or deceleration. One clunk while accelerating. One clunk while decelerating. No clunk with lateral G's in turns and no clunk with G forces up and down.
Recently, while opening the driver's side door, I heard the distinct sound of my elusive clunk. Upon further examination, it became apparent that minor flexing of the door hinge was causing some binding and a resulting pop/clunk. Liberal oil and grease on the upper and lower hinge made the clunk completely disappear.. Jeeze.