If you drive an Audi S4 or S5 B9 with the 3.0T turbocharged V6, you know the engine is already a powerhouse—but the factory downpipe is one of the biggest bottlenecks holding back its true performance. Our SS304 Catless High-Flow Downpipe is designed to eliminate restrictions, unlock power, and give your car the aggressive sound it deserves.
Why the Stock Downpipe Is Holding You Back
The factory downpipe on the S4/S5 B9 includes a restrictive primary catalytic converter that chokes exhaust flow, traps heat, and limits power output. Even with an ECU tune, the stock setup creates significant backpressure that slows turbo spool, kills throttle response, and muffles the 3.0T’s deep V6 tone.
Our catless downpipe removes these restrictions entirely, letting exhaust gases escape freely. The result is faster turbo response, noticeable horsepower and torque gains, lower underhood temperatures, and a raw, race-inspired exhaust note.
Key Features of Our S4/S5 B9 Catless Downpipe
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Premium SS304 Stainless Steel Construction
Built from thick, durable 304 stainless steel, this downpipe is hand TIG-welded for maximum strength, leak-free performance, and long-lasting corrosion resistance. It’s engineered to withstand extreme heat and vibration from daily driving and track use.
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Catless High-Flow Design
Eliminates the factory catalytic converter, replacing it with a smooth, straight-through path. This drastically reduces backpressure, allowing your turbos to spin faster and produce more power.
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Direct Fit, Bolt-On Installation
Precision-machined to match the factory mounting points of the 2017+ Audi S4/S5 B9. No cutting, no welding, and no modifications required. All necessary hardware, gaskets, and O2 sensor bungs are included for a seamless install.
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Optimized for the 3.0T V6
The pipe diameter and bend angles are specifically tuned for the S4/S5 B9’s turbo layout, ensuring smooth exhaust flow without creating turbulence or dead zones. This means you get maximum performance gains without sacrificing reliability.
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Unleash the True V6 Sound
Free from the stock cat’s muffling effect, this downpipe unlocks the deep, aggressive growl of the 3.0T engine. Paired with an aftermarket cat-back exhaust, you’ll get a raw, race-inspired tone that’s louder, deeper, and more satisfying than stock.
Performance Benefits You’ll Notice
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Faster Turbo Spool & Reduced Lag: Improved flow lets your turbo spin up faster, eliminating low-end lag.
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Horsepower & Torque Gains: Up to +20-35 HP gains when paired with a custom tune.
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Lower Exhaust Temperatures: Reduced backpressure lowers underhood heat, protecting your turbo and engine.
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Aggressive Exhaust Tone: Raw, deep V6 sound without the harsh drone of cheap aftermarket parts.
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Ideal for Tuned & Modified Builds: Perfect for ECU tunes, hybrid turbos, or full turbo-back exhaust setups.
