If the pieces are bronze in color then maybe they are part of the bushings from the turbos. They seem kinda big to get through the turbo oil lines though. I would be concerned about the turbos. Hopefully your replacing them. Could also be part of the bearings although these pieces seem to have gotten extremly hot and deformed so I think I would tend to suspect a part that is exposed to the extreme heat of the combustion chamber.
--Z is back upand running!
--Who ever said a house is going to be the biggest investment you'll ever make OBVIOUSLY never owned a Z!