N55 E Chassis Cen-Cal DownpipeCen Cal Motorsport N55 Downpipe E Chassis BMW Unlock hidden power and dramatically improve turbo spool with the Cen Cal Motorsport N55 Downpipe for E Chassis BMWs. Engineered for performance and built with high quality materials, this downpipe reduces backpressure and unleashes a more aggressive exhaust tonemaking it a must have for any N55 build. Key Features: 1. Performance Gains Significant horsepower and torque increases when paired with a tune.