BMW N54 Aluminum Boost Vacuum Tanks - 135i, 335i, 535i, 1M, Z4Replace your weak leaky plastic N54 vacuum tanks with upgraded metal cans! N54 powered BMW vehicles have two of these tanks, one for each turbo. They accumulate and hold vacuum air to be used on both turbos. The factory plastic N54 boost vacuum tanks tend to leak and cause problems. If vacuum can't be stored the wastegates will not function, leading to common low boost or overboost faults. We have the solution, the all new heavy duty BMS tanks.