Description
Designed for Mercedes-Benz and Mercedes-AMG M256 3.0T inline-six applications, including the AMG GT43, GT50, GT53, GLE53, S450, and S500, the Untd. Performance Catless Downpipe is an ideal upgrade for enthusiasts looking to reduce exhaust restriction, improve turbocharger response, increase horsepower potential, and enhance the sound of the M256 turbocharged inline-six.
By removing the restrictive factory catalytic converter and providing a significantly freer-flowing exhaust path from the turbocharger, the Untd. Performance Catless Downpipe helps reduce exhaust backpressure and allows the engine to evacuate exhaust gases more efficiently. When paired with an appropriate ECU tune, the downpipe can help unlock substantially greater performance from the M256 platform.
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 turbocharger. Reduced exhaust restriction helps minimize backpressure and allows the M256 engine to move exhaust gases more efficiently.
Improved Turbo Response & Performance:
The freer-flowing design allows the turbocharged 3.0T inline-six to expel exhaust gases more efficiently. Reduced backpressure can help improve turbocharger response, throttle response, horsepower, and torque, particularly when combined with an appropriate ECU calibration.
Enhanced M256 Exhaust Sound:
The catless design allows more of the M256’s natural exhaust character to come through, producing a deeper, louder, and more aggressive exhaust tone. Turbocharger spool and exhaust volume become more pronounced under acceleration.
Designed for the M256 3.0T:
Engineered for Mercedes-Benz and Mercedes-AMG applications equipped with the 3.0T M256 turbocharged inline-six, including GT43, GT50, GT53, GLE53, S450, and S500 applications.
48V EQ Boost Compatible Platform:
The M256 utilizes Mercedes-Benz’s 48V EQ Boost mild-hybrid system and electric auxiliary compressor. ECU tuning support and available calibrations can vary depending on model, model year, ECU software, and drivetrain configuration.
Durable Construction:
Built to withstand the high exhaust temperatures, pressure, and demanding conditions generated by the turbocharged M256 engine. Precision-welded construction is designed to provide reliable performance for both performance-oriented and competition applications.
Direct-Fit Design:
Engineered specifically around compatible M256 applications to provide a replacement for the factory downpipe configuration while maintaining compatibility with suitable OEM and aftermarket exhaust components.
Installation Hardware Included:
The downpipe includes the necessary clamps, bolts, and installation hardware where applicable to help provide a secure installation and proper sealing.
Tune Recommended / Required for Optimal Performance:
An ECU tune is strongly recommended when installing a catless downpipe. The factory ECU calibration will not fully take advantage of the increased exhaust flow. A suitable calibration can optimize boost control, ignition timing, fueling, throttle response, and overall performance.
Estimated Performance Gain
Depending on the vehicle configuration, ECU calibration, fuel quality, exhaust system, and supporting modifications, a properly tuned M256 can see meaningful horsepower and torque gains from the reduced exhaust restriction.
On the M256 platform, the largest gains are generally achieved when the downpipe is combined with a downpipe-specific Stage 2 ECU calibration designed to take advantage of the increased exhaust flow. Because the M256 platform incorporates 48V EQ Boost and an electric auxiliary compressor, tuning availability and final results may vary between specific applications.
| Configuration | Estimated HP Gain | Estimated Output |
|---|---|---|
| Stock Tune | ~5–12 HP | ~434–441 HP* |
| Stage 1 Tune | ~55–80 HP | ~484–509 HP* |
| Stage 2 / Downpipe-Specific Tune | ~75–105 HP | ~504–534 HP* |
Figures are estimated crank horsepower based on a 429 HP reference M256 application, 91–93 octane (95–98 RON) pump fuel, and stock turbocharger hardware. Actual results will vary depending on the specific vehicle’s factory power rating, ECU calibration, fuel quality, engine condition, supporting modifications, and dyno methodology.
Note: S450 and GT43 applications may have lower factory power ratings than the 429 HP reference configuration, so their absolute output will differ.
⚠️ Check Engine Light Warning
A Check Engine Light (CEL) is expected after installing a catless downpipe with the factory ECU calibration due to the removal of the catalytic converter and the resulting change in exhaust emissions readings.
A compatible ECU tune is strongly recommended to properly calibrate the vehicle after installation. A downpipe-specific Stage 2 calibration may require rear-O2 / catalyst monitoring to be disabled to prevent 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 are designed primarily around emissions control, noise requirements, and factory operating specifications. These components can create additional exhaust restriction, particularly as engine airflow and boost pressure increase.
The Untd. Performance Catless Downpipe provides a significantly freer-flowing exhaust path from the turbocharger, helping reduce exhaust backpressure and improve exhaust gas evacuation.
On an otherwise stock vehicle, the factory ECU may only realize a modest increase in performance because the calibration is not designed to take full advantage of the additional airflow. When combined with an appropriate ECU tune, however, the downpipe can become an important supporting modification for extracting additional performance from the Mercedes-Benz M256 3.0T turbocharged inline-six.
Compatibility
- Mercedes-AMG GT43 – M256 3.0T
- Mercedes-AMG GT50 – M256 3.0T
- Mercedes-AMG GT53 – M256 3.0T
- Mercedes-AMG GLE53 – M256 3.0T
- Mercedes-Benz S450 – M256 3.0T
- Mercedes-Benz S500 – M256 3.0T
- Mercedes-Benz / Mercedes-AMG M256 3.0T Inline-Six Applications
- 2017+ M256 3.0T Applications where applicable
Fitment may vary depending on model year, engine code, drivetrain, transmission, ECU software, emissions equipment, and existing exhaust modifications. Please verify compatibility before ordering.
⚠️ Important Notice
CATLESS / OFF-ROAD USE ONLY: This product eliminates the factory catalytic converter 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 the specific M256 application, factory power rating, ECU calibration, fuel quality, supporting modifications, engine condition, and dyno conditions.
The M256 platform incorporates 48V EQ Boost and an electric auxiliary compressor, and tuning support can vary between specific models and ECU software versions.
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.
Reviews
There are no reviews yet.