I don't know why I did not see
this before when searching about the tanks.
I already had mine replaced under warranty and it became a big issue a few months later after it had leaked on the injectors and they failed. The dealer blamed my tune and said I had a blown head gasket which caused "overpressurization" of the tank. They wanted $9,000+ to fix it. I brought it to BMW of NYC (which is owned by BMW) and they fixed it under warranty and confirmed that I did not have a blown head gasket.