Description
Designed for the Mercedes-Benz AMG W218 CLS63 5.5T 4MATIC, the Untd. Performance Catless Downpipe is an ideal upgrade for enthusiasts looking to improve turbocharger response, increase horsepower potential, and unleash a more aggressive version of the AMG V8 sound.
By removing the restrictive factory catalytic converters and providing a freer-flowing exhaust path from the turbochargers, the Untd. Performance Catless Downpipe helps reduce exhaust backpressure and allows the twin-turbocharged engine to expel exhaust gases more efficiently.
Key Features
Catless Design – Maximum Exhaust Flow:
The Untd. Performance Catless Downpipe eliminates the restrictive factory catalytic converter, creating a significantly freer-flowing exhaust path from the turbochargers. Reduced exhaust restriction helps minimize backpressure and allows the engine to move exhaust gases more efficiently.
Improved Turbo Response & Performance:
The freer-flowing design allows the twin-turbocharged 5.5T engine to expel exhaust gases more efficiently. When paired with an appropriate ECU tune and supporting modifications, reduced restriction can help improve turbo response, throttle response, horsepower, and torque.
Aggressive AMG V8 Sound:
The catless design significantly enhances the character of the AMG V8, producing a deeper, louder, and more aggressive exhaust tone. Turbocharger spool, exhaust volume, and overall engine character become more pronounced under acceleration.
Durable Construction:
Built to withstand the high temperatures, exhaust pressure, and demanding conditions generated by the twin-turbocharged AMG engine. Precision-welded construction provides dependable performance for both street-performance and competition-oriented applications.
Direct-Fit Design:
Engineered specifically for compatible Mercedes-Benz AMG W218 CLS63 5.5T 4MATIC applications, providing a direct replacement for the factory downpipe configuration and designed to work with suitable OEM and aftermarket exhaust components.
Installation Hardware Included:
The downpipes include clamps, bolts, and required installation hardware to help ensure a proper fit and secure installation. Supplied hardware helps simplify installation while providing the necessary components for proper sealing and mounting.
Tune Recommended / Required for Optimal Performance:
An ECU tune is strongly recommended and may be required when installing catless downpipes. Proper calibration allows the twin-turbocharged engine to take full advantage of the increased exhaust flow while optimizing boost control, fueling, throttle response, and overall performance.
Estimated Performance Gain
Depending on the turbocharger configuration, ECU calibration, fuel quality, exhaust system, and supporting modifications, a properly tuned vehicle may see meaningful horsepower and torque gains from the reduced exhaust restriction.
For the Mercedes-AMG 5.5T M157 platform, the largest gains are generally achieved when the downpipe is combined with an appropriate Stage 2 calibration that is specifically designed to take advantage of the increased exhaust flow. The tune may also require rear-O2 / catalyst monitoring to be disabled for proper calibration after removal of the factory catalytic converters.
| Configuration | Estimated HP Gain | Estimated Output |
|---|---|---|
| Stock Tune | ~10–20 HP | ~587–597 HP |
| Stage 1 Tune | ~80–110 HP | ~657–687 HP |
| Stage 2 / Downpipe-Specific Tune | ~110–150 HP | ~687–727 HP |
Figures are estimated crank horsepower based on 91–93 octane (95–98 RON) pump fuel and stock turbochargers. Actual results will vary depending on the specific factory power rating, engine condition, ECU calibration, fuel quality, supporting modifications, and dyno methodology.
⚠️ Check Engine Light Warning
A Check Engine Light (CEL) may occur after installing these catless downpipes due to the removal of the factory catalytic converters and the resulting change in exhaust emissions readings.
A compatible ECU tune is recommended and may be required to properly calibrate the vehicle after installation and address catalyst-efficiency-related fault codes. Tune requirements can vary depending on model year, ECU software, emissions equipment, and existing modifications.
For optimal performance, drivability, and compatibility, professional ECU tuning is recommended.
Why Upgrade?
The factory downpipe and catalytic converter configuration is designed primarily around emissions control and factory operating requirements. These components can create additional restriction in the exhaust system, particularly as engine power and turbocharger airflow increase.
The Untd. Performance Catless Downpipe provides a significantly freer-flowing exhaust path from the turbochargers, helping reduce exhaust backpressure and improve exhaust gas evacuation.
When combined with an appropriate ECU tune, upgraded turbochargers, and supporting modifications, the downpipes can provide an excellent foundation for extracting additional performance from the Mercedes-AMG 5.5T twin-turbocharged V8.
Compatibility
- Mercedes-Benz AMG CLS63 – W218 – 5.5T M157
- Mercedes-Benz AMG CLS63 – W218 – 5.5T M278 Applications
- CLS63 AMG 4MATIC – 2013–2017
- Mercedes-AMG 5.5T Twin-Turbo V8 Applications
Fitment may vary depending on model year, engine code, drivetrain, transmission, emissions equipment, ECU software, and existing exhaust modifications. Please verify compatibility before ordering.
⚠️ Important Notice
CATLESS / OFF-ROAD USE ONLY: This product eliminates the factory catalytic converters and may not be legal for use on public roads in your jurisdiction. Check your local emissions, inspection, and vehicle regulations before installation.
A Check Engine Light may occur without appropriate ECU calibration. A compatible tune may be required for proper operation and optimal performance.
PERFORMANCE GAINS ARE ESTIMATES: Actual horsepower and torque gains will vary depending on turbocharger configuration, ECU calibration, fuel quality, supporting modifications, engine condition, and dyno conditions.
Professional installation and ECU calibration are recommended.
Untd. Performance is not responsible for emissions compliance, inspection requirements, or the legality of installing or operating this product on public roads.
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