HKS 3" Catless Stainless Steel Down PipeThe K20C engine was designed for use in a normal road car and features a catalytic converter, removing this converter eliminates its restricting effects which significantly increases the engine horsepower. HKS developed an extension pipe without the catalytic converter and a frontpipe that will connect it to a catback exhaust system. Features: Removing catalytic converter results in a more linear boost and throttle response. Uses 3 inch pipes,