+1
Mine was tapping like a motherf**ker after a track day at Eastern Creek. Tapping increased with revs too (louder and faster). Only slight loss in power. Wouldn't boost as much either.
Blew out all the exhaust gaskets: engine to manifold, manifold to turbo, turbo to gate, turbo to dump.
Had all gaskets replaced with steel ones and all was good again.
Fingers crossed this is what the problem is with yours miss.