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Stainless Steel Racing Catalyst, B9 Audi S4/S5


Product Description:

The 034Motorsport Stainless Steel Racing Catalyst for B9 Audi S4/S5 is designed as a drop-in replacement for the restrictive factory catalytic converter. The Stainless Steel Racing Catalyst offers increased horsepower and torque throughout the powerband, reduced turbocharger lag, improved throttle response, and an enhanced exhaust note. This upgrade eliminates the primary flow limitation in the factory exhaust system, allowing you to maximize the potential of your turbocharged engine.

Optimized for increased flow and maximum performance, the Stainless Steel Racing Catalyst features a massive 148mm diameter Euro 4 racing catalytic converter in the factory location. This complete drop-in solution includes an integrated v-band flange at the turbine outlet, integrated oxygen sensor bung after the catalyst, integrated 3-bolt downpipe flanges, and a complete gasket/hardware kit to allow for precise fitment and ease of installation. The Stainless Steel Racing Catalyst for B9 Audi S4/S5 vehicles is constructed from 304 stainless steel for maximum durability and corrosion resistance, is TIG-welded, and includes an integrated OE style heat isolation barrier  to minimize exhaust heat transferred into the engine bay.

034Motorsport's Stainless Steel Racing Catalyst was developed entirely in-house on 034Motorsport's Development B9 Audi S4 utilizing the latest in 3D Scanning Technology, CAD Software, and Rapid Prototyping Techniques. Final production units were then tested extensively on track in B9 Audi S4 vehicles before release.


  • Increased Horsepower & Torque Throughout the Powerband (+ 21 HP / + 33 TQ Peak)
  • Quicker Turbocharger Spool & Faster Transient Response (150-300 RPM Quicker Spool)
  • Enhanced Exhaust Note & Turbocharger Sounds
  • Direct, Bolt-In Upgrade for Factory Catalytic Converter
  • Engineered In-House by 034Motorsport's Engineering Team
  • Factory-Location 148mm Euro 4 Racing Catalytic Converter
  • 304 Stainless Steel Construction with Integrated Inlet/Outlet Flanges & O2 Sensor Bung
  • Precision CNC-Machined Flange Mating Surfaces
  • OE Style Heat Isolation Barrier
  • TIG Welded & Backpurged

What's Included:

  • 034Motorsport Stainless Steel Performance Downpipe
  • Integrated Euro 4 Racing Catalytic Converter
  • Factory Turbocharger Outlet Gasket
  • Factory Catalyst to Downpipe Gaskets (2)
  • M8 Locknuts (6)
  • M8x30 Socket Head Cap Screws (4)
  • M8 Washers (4)

034Motorsport B9 Audi S4 3.0 TFSI Race Catalyst Performance Comparisons

These Performance Comparisons were performed using an in-house 2018 Audi S4 3.0 TFSI on 91 Octane fuel.

  Factory Catalyst (91 Octane) 034 Race Catalyst (91 Octane)
Peak Horsepower 304 HP 320 HP
Peak Torque 332 FT-LBS 348 FT-LBS
Peak HP Gains vs. Factory Catalyst - 21 HP @ 5,680 RPM
Peak TQ Gains vs. Factory Catalyst - 33 FT-LBS @ 2,525 RPM

Factory Catalyst vs. 034 Race Catalyst - 91 Octane

034 Race Catalyst Power Gains - 91 Octane

Supported Vehicles

  • 2018 - Present Audi S4 (B9)
    • 3.0 TFSI
  • 2018 - Present Audi S5 (B9)
    • 3.0 TFSI

Emissions Disclaimer

  • This product is sold for off-road use only.
  • By purchasing this product, you understand this product is sold for competition use and is not legal for use in highway or street vehicles.
  • This product will cause a check engine light (MIL) on the stock factory tuning. A racing ECU calibration for offroad use only is required to eliminate the check engine light.

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