KYOSTAR 4" Catless Downpipe for 2012-2017 BMW F30 F31 F34 320i 328i 420i 428i N20 2.0T The KYOSTAR 4" Catless Downpipe is designed for BMW F-Series models equipped with the N20 2.0T turbocharged engine. Featuring a high-flow 4-inch pipe design, this downpipe improves exhaust flow efficiency by removing the factory catalytic restriction, helping reduce backpressure and improve turbo response. It is engineered for BMW enthusiasts looking to maximize turbocharger performance and