CTS Turbo B6 Audi A4 1.8T High Flow Cat Pipe

The CTS B6 A4 1.8T High Flow Cat Pipe is the premier cat pipe for your Audi. Our high-flow cat is designed to seamlessly fit in place of your restrictive stock catalytic converter, which is situated immediately after the turbocharger.  Our high-flow cat features 3" stainless steel piping, smooth mandrel bends, two 02 sensor bungs with an option for a third.  Substantial power gains, improved exhaust flow and a more throaty sound are the main benefits of installing our high-flow cat.  Upon inspection you will notice a flare which is nearly 4", this flare then tapers to 3" and is designed to allow for optimal flow as the exhaust gas transitions from the turbocharger to the high-flow cat.  In addition to being one of the best bang for the buck performance upgrades for A4 owners, our cat pipe is also a very attractive piece.  Each 3" high-flow cat is mandrel-bent, hand tig welded.  Do you need an additional 02 bung for data logging?  Well, that's no problem!  Tig welding additional 02 bungs can be done for an additional charge. Fitment: 2002 - 2005 B6 Audi A4 1.8T Product Details: T304 stainless steel construction Mandrel-bent stainless steel Fully tig welded design Optional third 02 bung Install hardware included Great power upgrade To remove the CEL that will occur, proper tuning software must be used. The use of stage 2 software upgrade is strongly recommended.

This part also goes by the following cross reference.

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Fits These Vehicles 2 applications

A4

Make	Model	Engine	Years
AUDI	A4		2002–2005
AUDI	A4 (B6)		2002–2005

Fitment data last updated: 2026-06-29