Here is a picture from the thread of the "reputable" person that tore down an N54. This is pulled right from his thread. Just because a person takes their engine apart does not mean they know what they are looking at. This picture is directly from that rebuild thread. This piston/rod combo they state is FORGED. It indeed is NOT. You can clearly see the casting in the rod and piston. If you do not know the difference between forged and cast maybe you should do a google search
Here is said picture.
Now this picture below is a FORGED piston and rod( this is not out of a BMW but doesnt matter), see the difference in the metal?