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Stainless Valved Catback Exhaust System for Audi B9 S4 S5 by Stratec Systems
SKU: 721814382440
$1,999.95 USD
Shipping calculated at checkout.
The Audi B9 S4 and S5, powered by the EA839 3.0L V6, offer strong performance from the factory—but the stock exhaust limits the engine’s true sound and character. The STRATEC Valved Exhaust System unlocks a more aggressive, performance-driven exhaust tone while retaining refined, OEM-like manners when desired.
Engineered as a complete, one-piece exhaust system, this setup runs from the downpipe connection to the exhaust tips, eliminating the need to mix components from multiple suppliers. The result is consistent sound quality, proper fitment, and seamless performance.
With valves open, expect a bold, motorsport-inspired exhaust note with pronounced overrun crackles. With valves closed, the system returns to a quiet, refined tone suitable for daily driving—without unwanted drone when paired with the factory downpipe.
Why It Works
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Complete One-Piece System: No mixing of axle-backs or resonators
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Electronic Valve Control: Instantly switch between aggressive and refined sound
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Mandrel-Bent Design: Optimized exhaust flow for improved throttle response and power
Sound & Control
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Valves Open: Aggressive tone with strong midrange and sharp overrun crackles
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Valves Closed: Quiet, refined, and OEM-like for daily driving
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No Drone: When used with the factory downpipe
Construction & Details
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Material: Full T304 stainless steel construction
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Weight Savings: Approx. 16.4 lbs lighter than factory exhaust
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Craftsmanship: Precision TIG welding and smooth mandrel bends
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Exhaust Tips: Includes premium tips for a clean, performance-oriented finish
Vehicle Fitment
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2017–2024 Audi S4 (B9)
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2018–2024 Audi S5 (B9)
STRATEC Systems FAQ
WHO IS STRATEC SYSTEMS?
STRATEC Systems is an automotive performance brand focused on premium upgrades for exotic, European, and high-performance vehicles. Their product line includes exhaust systems, carbon fiber components, aerodynamic upgrades, steering components, and other performance-focused parts for platforms including BMW, Mercedes-AMG, Chevrolet Corvette, McLaren, Lamborghini, Ferrari, and others.
WHAT TYPES OF PRODUCTS DOES STRATEC OFFER?
STRATEC offers a broad range of performance and appearance upgrades. Depending on the vehicle, their catalog can include titanium and stainless steel exhaust systems, downpipes, midpipes, headers, carbon fiber aerodynamic components, body components, steering upgrades, and other specialty performance parts.
WHAT MATERIALS DOES STRATEC USE?
Materials vary by product. STRATEC uses materials such as titanium, 304 stainless steel, carbon fiber, prepreg carbon fiber, and other application-specific materials. Always refer to the individual product description for the exact construction and finish of the part being purchased.
ARE STRATEC PARTS VEHICLE SPECIFIC?
Many STRATEC products are engineered for specific vehicle platforms, model years, engines, or body styles. Some products may have broader or universal applications. Always verify the fitment information listed on the individual product page before ordering.
DO STRATEC EXHAUST SYSTEMS REQUIRE MODIFICATION?
Installation requirements depend on the specific exhaust system and vehicle. Many STRATEC systems are designed as direct-fit or bolt-on replacements, while certain applications may require transferring factory components, calibration, additional hardware, or other installation procedures. Refer to the individual product description for application-specific requirements.
HOW DO STRATEC VALVED EXHAUST SYSTEMS WORK?
On applicable systems, exhaust valves allow the vehicle to switch between a more controlled exhaust tone and a more aggressive sound profile. Operation varies by application. Some systems integrate with factory valve controls, while others may use application-specific valve hardware or controls. Check the individual product listing for details.
IS PROFESSIONAL INSTALLATION RECOMMENDED?
Yes. Professional installation is recommended for STRATEC performance, exhaust, carbon fiber, and aerodynamic components. Proper installation helps ensure correct fitment, alignment, clearance, valve operation where applicable, and protection of the component and vehicle.
DO CARBON FIBER PARTS REQUIRE TEST FITTING?
Yes. Carbon fiber and exterior body components should always be carefully test fitted before final installation. Vehicle tolerances, previous body work, mounting points, and component alignment can affect final fitment. Professional installation is strongly recommended for larger aerodynamic and body components.
ARE STRATEC PERFORMANCE PARTS STREET LEGAL?
Street legality and emissions compliance depend on the specific product, vehicle, and local regulations. Certain exhaust or emissions-related components may be intended for competition or off-road use only. Customers are responsible for confirming that a product is legal for use on their vehicle in their jurisdiction before installation.
HOW DO I MAKE SURE I ORDER THE CORRECT STRATEC PART?
Review the vehicle, chassis, engine, model year, body style, and any other fitment information listed on the product page. If there is any uncertainty, contact FI Performance before ordering so fitment can be reviewed for your specific vehicle.
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