....hhmmmmm, I wish I understood the reasons for the different BMW designs.
So your 325 has two pipes with no crossover, my 328 has a crossover after the two cats and your M54B30 has a 2 into 1 before the two cats and then two separate paths after? (or is that a fancy crossover before the cats?).
It looks from that picture this system also has a smaller diameter pipe for the rear bank of three cylinders?
I guess as your planning to upgrade to the M54B30 anyway so this is probably an irrelevant discussion
