In the middle of re-powering my 523i touring with an M54B30 and need to sort out the fuel system.
As the M54 is returnless (as opposed to the M52), and the fuel pressure regulator is integrated into the fuel pressure regulator, the fuel lines are different.
I'm looking for the highlighted parts in the following diagram, which are found in any later-model E39s with an M54 or M62 engine: