GESI Catted Downpipe Bellmouth

The COBB Tuning GESI Catted Downpipe Bellmouth is engineered as a direct replacement for the restrictive stock downpipe on the 2007-2013 Mazdaspeed3 MZR DISI 2.3T MT. This high-performance unit features a bellmouth entry, which provides a smooth transition from the turbocharger's turbine outlet to the downpipe. This design significantly reduces backpressure compared to the factory unit's abrupt transition, leading to improved turbocharger efficiency and faster boost onset. Equipped with a GESI (Government Emissions Specification) catalytic converter, this downpipe maintains emissions compliance for street use while offering substantially lower flow restriction than the OEM catalytic converter. The downpipe is constructed from durable 304 stainless steel with a 3.00-inch inner diameter. It is designed to integrate seamlessly with Cobb Accessport Mazdaspeed3 Stage 2 OTS maps, though tuning is not strictly required, it is recommended for optimal performance. All necessary gaskets, bolts, and hardware are included for a complete installation.