The K&N 57S Performance Airbox replaces the original airbox with a fully enclosed, purpose designed, injection moulded airbox and K&N high flow filter. The enclosed airbox means cool air is retained and fed to the engine without external heat sources affecting inlet temperatures. The oversized conical filter and the custom engineered Velocity Stack (Velum) have been designed to increase, smooth, and straighten airflow - allowing maximum cool air for increased power. By reducing both the air filter and air box restriction, these systems provide up to three times the power gains available with a K&N replacement air filter.
K&N's 57S Performance Airbox is a TUV compliant intake system. This innovative design delivers extra power and complies with the latest TUV emissions and sound suppression regulations.
Every K&N 57S Air Box comes with K&N's Million Mile Limited Warranty
- Car Make: BMW
- Car Model: 4-Series (F32/33/36/82)
- Engines: 420i, 428i
- Part Number: 57s-2001