Our Mazda MX-5 Decat Manifold replaces the standard restrictive manifold and catalytic converter with a stainless steel tubular manifold and decat. Fitting a tubular manifold and replacing the restrictive catalytic converter with a decat allows the exhaust gasses to flow much more freely, increasing the power output of the engine and improving throttle response in the process. Features: TIG welded Constructed from T304 stainless steel 4-2-1 design (offers greater mid range gains than a 4-1 design) Improved throttle response and gas flow Gaskets and bolts included