CTS Turbo High Flow Catalytic Converter – Audi B8/B8.5 A4 / A5 / Allroad / Q5 | 1.8T / 2.0T TFSI

Unlock more power and improve exhaust flow on your B8 or B8.5 Audi with the CTS Turbo High Flow Catalytic Converter. Engineered specifically for the 1.8T and 2.0T TFSI-equipped A4, A5, Allroad, and Q5, this high-flow cat replaces the restrictive factory catalytic converter with a higher-cell-count, free-flowing unit that reduces exhaust backpressure while retaining catalytic function — a meaningful performance upgrade that pairs perfectly with a tune, downpipe, or full exhaust system build.

Key Features:

• High-flow catalytic converter — significantly less restrictive than the factory cat while retaining catalytic function
• Application-specific fitment — engineered for the B8/B8.5 Audi A4, A5, Allroad, and Q5 with 1.8T or 2.0T TFSI engine
• Direct bolt-on replacement — uses factory mounting points and flanges for a clean, no-fabrication installation
• Retains catalytic function — high-flow substrate maintains emissions reduction capability while improving flow versus OEM
• CTS Turbo engineering — designed by one of the most respected names in VAG performance parts
• Pairs with CTS downpipe and exhaust — designed to work seamlessly with CTS Turbo’s full B8 exhaust lineup

Performance Benefits:

• Reduced Exhaust Backpressure: High-flow substrate allows exhaust gases to pass through more freely than the factory cat, reducing backpressure and improving turbocharger spool and power output
• Improved Turbo Response: Less exhaust restriction means the turbocharger can spool faster and more efficiently, improving throttle response and mid-range power delivery
• Tuning Headroom: Reduced exhaust restriction gives your tuner more room to optimize boost, timing, and fuelling for additional power gains
• Retains Catalytic Function: Unlike a test pipe or cat delete, the high-flow cat maintains emissions reduction capability — a more street-friendly solution for daily-driven builds
• Exhaust Note: Improved flow contributes to a slightly more open, refined exhaust tone without the drone or harshness of a full cat delete

Specifications:

• Brand: CTS Turbo
• Part Number: CTS-EXH-TP-0004-B8-CAT
• Type: High Flow Catalytic Converter
• Engine Compatibility: 1.8T TFSI / 2.0T TFSI (EA888 and EA113 series)
• Fitment Style: Direct bolt-on replacement
• Catalytic Function: Retained (high-flow substrate)

Fitment Information:

• Audi A4 B8 / B8.5 — 1.8T TFSI / 2.0T TFSI
• Audi A5 B8 / B8.5 — 1.8T TFSI / 2.0T TFSI (Coupe, Cabriolet, Sportback)
• Audi Allroad B8 / B8.5 — 2.0T TFSI
• Audi Q5 B8 — 2.0T TFSI
• Note: Verify your specific year, model, and engine variant before ordering. Some model years may have different exhaust configurations.
• Installation: Professional installation recommended
• Tune: ECU tune recommended after installation to take full advantage of reduced exhaust restriction

What’s Included:

• CTS Turbo high flow catalytic converter
• Installation hardware (where applicable)
• Installation instructions

Installation Notes:

• Allow the exhaust system to cool completely before beginning installation
• Apply anti-seize to all exhaust fasteners before installation
• Inspect all gaskets and replace if worn or damaged
• An ECU tune is recommended after installation to optimize for the improved exhaust flow
• A CEL for catalyst efficiency may appear depending on your tune and O2 sensor configuration — address with an appropriate tune or O2 spacer
• Professional installation recommended

High Flow Cat vs. Cat Delete:

A high-flow catalytic converter offers a middle ground between the factory cat and a full cat delete (test pipe). The factory cat uses a dense substrate that restricts exhaust flow significantly — particularly on turbocharged applications where exhaust backpressure directly affects turbo spool and power. A high-flow cat uses a less dense substrate that allows significantly more flow while retaining the catalytic converter’s emissions reduction function. For daily-driven builds or vehicles that need to pass emissions testing, a high-flow cat is the practical performance upgrade — meaningful power gains without the legal and emissions complications of a full cat delete.

The B8/B8.5 EA888 Platform:

The B8 and B8.5 Audi A4, A5, Allroad, and Q5 with 1.8T and 2.0T TFSI engines represent one of the most popular VAG tuning platforms in the enthusiast community. The EA888 (and earlier EA113) turbocharged four-cylinder responds exceptionally well to bolt-on modifications — intake, intercooler, downpipe, and exhaust upgrades combine with a tune to produce significant power gains from a relatively modest factory output. The CTS Turbo high-flow cat is a key component in any B8 exhaust build, reducing one of the most significant remaining restrictions in the factory exhaust system.

Why CTS Turbo?

CTS Turbo is one of the most respected names in VAG (Volkswagen Audi Group) performance parts, with a comprehensive lineup of intake, intercooler, turbo, and exhaust components for Audi, Volkswagen, and SEAT platforms. Their B8 exhaust components are engineered specifically for the platform — not adapted universal parts — ensuring proper fitment, correct flange dimensions, and compatibility with the rest of the CTS exhaust lineup.

Perfect For:

• B8/B8.5 Audi A4, A5, Allroad, and Q5 owners building a performance exhaust system
• 1.8T and 2.0T TFSI builds seeking improved exhaust flow while retaining catalytic function
• Daily-driven builds that need to pass emissions testing but want meaningful exhaust performance gains
• Builds pairing with a CTS downpipe, intake, and tune for a complete Stage 2 setup
• Anyone replacing a worn, damaged, or clogged factory catalytic converter with a performance upgrade

Pro Tip: Pair with a CTS Turbo downpipe and intake for a complete Stage 2 exhaust build. The combination of high-flow cat, performance downpipe, and tune delivers the most significant power gains available from bolt-on exhaust modifications on the B8 TFSI platform.

Note: An ECU tune is strongly recommended after installation. Running factory maps with a high-flow cat leaves power on the table and may trigger a catalyst efficiency CEL depending on your O2 sensor configuration.