K&N 57-0618-1 Performance Air Intake System VW GOLF 1.9TDI/230TDIDescription K&N 57 0618 1 Performance Air Intake System VW GOLF 1. 9TDI 230TDI K&N 57i Series induction kits are specifically engineered for each vehicle to eliminate the size restrictions of the factory air box. These kits are designed in various forms depending on vehicle characteristics and available engine bay space. Each kit delivers power across the RPM range. The open air filter design provides increased airflow with lower restriction compared