Ok, I didn't realize the original water pump pulley was plastic! Yes, already have the water pump with metal impeller ready to go. Good to know that wahler is the OE for the thermostat but too late, already ordered the BMW for almost double the money, crap ;( I didn't want to take a chance on that. The expansion tank on mine looks like it might have been replaced, looks newer and has BMW parts sticker on it. Did BMW have a change up on the expansion tank ?