Catted & High-Flow Cat Downpipes

Downpipes that keep a catalytic converter, or that are offered with a catted option, are grouped here. Listings name the cat where the supplier gives it: high-flow cats, 200-cell, 300-cell and 400-cell. Some products are sold...

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About Catted & High-Flow Cat Downpipes

Downpipes that keep a catalytic converter, or that are offered with a catted option, are grouped here. Listings name the cat where the supplier gives it: high-flow cats, 200-cell, 300-cell and 400-cell. Some products are sold as either catless or catted, so pick the catted option on the product page.

Coverage includes BMW S58, B58, S68 and S63 engines, Audi S4/S5, RS5, RS6 and Q8, Mercedes-AMG E63, GT, GT53 and G63, the Porsche 718, 911 and Macan, and Ferrari, Lamborghini and McLaren models. Brands are STRATEC Systems, IRL, Palenon Performance, Spool Performance and Rvng RaceWorks. Catless and high-flow downpipes are intended for off-road / competition use and may not be legal for road use in your area.

See all exhaust and downpipes.

Frequently asked questions

What is the difference between catless, 200-cell and 400-cell downpipes?

The cell number is how many channels per square inch the converter core has. A catless (race) pipe has no converter and flows the most, with the most sound, rasp and smell. A 200-cell pipe keeps an open high-flow core, and a 300 or 400-cell pipe is denser and the most refined, closest to stock manners.

Is a catted downpipe quieter than a catless one?

Yes. The converter core absorbs some of the sound and takes the harsh edge off the tone. A 400-cell pipe is generally quieter and more refined than a 200-cell pipe, and both are quieter than a race pipe. Drone at cruise depends more on the rest of the exhaust than on the downpipe alone.

Will a catted downpipe pass inspection?

Do not assume it will. High-flow converters are not the same as certified replacement parts, and some listings note that no CARB EO number is listed. Catless and high-flow downpipes and other emissions-related parts are intended for off-road and competition use and may not be legal on the street where you live.

Do I need a tune for a catted downpipe?

A tune is recommended. A high-flow converter still changes what the rear oxygen sensor sees, so a check-engine light may occur, and several listings recommend a supporting tune. Check the listing for your part and speak with your tuner before installing. Factory-style catted replacements are designed to keep stock behavior.

Do the downpipes reuse the factory oxygen sensors and hardware?

Most downpipes reuse the factory oxygen sensors, so have an O2 sensor socket ready; seized sensors are common on older exhausts. Some pipes add sensor bungs, extensions or heat shields that change how the sensors fit, so check the listing for your part, and inspect the factory clamps and gaskets while everything is apart.