The Helix Catted Downpipe incorporates Helix Power’s first-rate bell-mouth downpipe, with the addition of a 200 cell Metal-Substrate high-flow catalytic converter and thermal barrier heat-shield.  The 200 cell Metal-Substrate downpipe has been tested by us to yield 7-10whp over the factory twin cats, while able to pass stringent California smog standards on the WRX / STI.  The thermal barrier heat-shield assists in rapid warm-up of the cat for maximum efficiency and helping to reduce engine bay temperatures.

Manufacturer's limited warranty