When you first start modifying the B7 A4 platform, its best to know what direction you want to take before starting off on your adventure. Last week we went over intakes and when/if you need one. This week will be the same involving high flow catalytic converters (HFC).

In terms of power goals, the stock catalytic converter is fine for a stage 1 build. Which is generally around the 250-270 wheel horsepower (whp) mark. However, once you enter a stage 2 build it is almost always mandatory to have a HFC. This is due to the increase in boost pressure; the turbo needs an easier path to dispose of the exhaust gases. Without a HFC, the turbo would experience lag and premature wear on the internals.

As far as options go, multiple companies have created their own version of a HFC with varying cell counts. The top three HFC’s for the B7 A4 platform that I have seen were designed by 034 Motorsport, ECS Tuning, and CTS Turbo.

My recommendation to you is to watch some videos on the sound quality of the HFC and get a feel for the sound. If possibly, go out to a car meet, find a B7 A4 owner, and see what is done to their build. I guarantee they will have no issue talking about their Audi.

-Devan