OAO High Performance Downpipes for Mercedes-Benz ML550 / GL550 / GLS550 / ML63 AMG / GL63 AMG / GLS63 AMG M278 & M157 Twin-Turbo V8 T304 Stainless Steel Exhaust System

Unleash the Full Power of Mercedes-Benz Twin-Turbo V8 Performance

Engineered for Mercedes-Benz luxury SUVs equipped with the powerful M278 4.7L Bi-Turbo V8 and AMG M157 5.5L Bi-Turbo V8 engines, the OAO High Performance Downpipes are designed to maximize exhaust flow, reduce turbocharger backpressure, and unlock the true performance potential of your vehicle.

Replacing the restrictive factory downpipes allows exhaust gases to exit the turbochargers more efficiently, improving turbo response, increasing engine efficiency, and delivering a deeper, more aggressive V8 exhaust note.

Manufactured from premium T304 stainless steel with precision TIG welding and CNC-machined flanges, every OAO downpipe is built for exceptional durability, superior heat resistance, and OEM-quality fitment.

Key Features

✓ Designed for Mercedes-Benz M278 & M157 Twin-Turbo V8 Platforms

✓ Premium T304 Stainless Steel Construction

✓ High-Flow Performance Downpipes

✓ Available in Catless or High-Flow Sport Catalytic Versions

✓ Precision TIG Welded

✓ Mandrel-Bent Tubing

✓ CNC Precision-Machined Flanges

✓ Reduced Exhaust Backpressure

✓ Improved Turbocharger Efficiency

✓ Faster Turbo Response

✓ Enhanced Exhaust Sound

✓ Direct Bolt-On OEM Fitment

Why Upgrade Your Downpipes?

The factory downpipes are designed to meet emissions and noise regulations, creating exhaust restriction immediately after the turbochargers.

The OAO High Performance Downpipes significantly improve exhaust gas evacuation, allowing the turbochargers to operate more efficiently while improving overall engine performance.

Potential benefits may include:

• Faster Turbo Spool

• Reduced Exhaust Restriction

• Improved Exhaust Flow

• Sharper Throttle Response

• Increased Mid-Range Torque

• Improved High-RPM Performance

• Enhanced Turbo Efficiency

• Better Compatibility with ECU Calibration and Performance Exhaust Systems

Actual performance improvements may vary depending on supporting modifications and ECU tuning.

Precision Performance Engineering

Developed using advanced exhaust flow simulation and motorsport engineering principles, the OAO downpipes maximize efficiency while maintaining excellent fitment.

Engineering highlights include:

• Large-Diameter High-Flow Tubing

• Smooth Exhaust Gas Transition

• Reduced Flow Turbulence

• Lower Exhaust Backpressure

• Improved Thermal Management

• Enhanced Turbocharger Performance

• Compatible with Factory and Aftermarket Cat-Back Exhaust Systems

Signature Twin-Turbo V8 Sound

The OAO Downpipes dramatically enhance the character of both the M278 and AMG M157 V8 engines.

Drivers may experience:

• Deeper Cold Start

• Stronger Twin-Turbo V8 Tone

• Enhanced Turbo Spool Sound

• Sharper Acceleration Note

• More Aggressive Overrun Crackles (ECU Calibration Dependent)

• Increased Exhaust Volume

• Improved High-RPM Exhaust Character

Whether installed on a luxury GLS550 or a high-performance GLS63 AMG, the result is a richer, more powerful V8 soundtrack.

Premium T304 Stainless Steel Construction

Manufactured from motorsport-grade T304 stainless steel to withstand extreme temperatures and demanding driving conditions.

Advantages include:

• Excellent Corrosion Resistance

• Superior Heat Resistance

• High Structural Strength

• Long Service Life

• Precision CNC-Machined Flanges

• Fully TIG Welded Construction

Every OAO downpipe undergoes strict quality inspection before shipment.

Vehicle Fitment

M278 4.7L Bi-Turbo V8

Compatible with:

• Mercedes-Benz ML550

• Mercedes-Benz GL550

• Mercedes-Benz GLS550

M157 5.5L Bi-Turbo AMG V8

Compatible with:

• Mercedes-Benz ML63 AMG

• Mercedes-Benz GL63 AMG

• Mercedes-Benz GLS63 AMG

Model Years

• ML550 (W166): 2012–2015

• GL550 (X166): 2013–2016

• GLS550 (X166): 2017–2019

• ML63 AMG (W166): 2012–2015

• GL63 AMG (X166): 2013–2016

• GLS63 AMG (X166): 2017–2020

Please verify your vehicle model, production year, and engine before ordering.

Package Includes

• OAO High Performance Downpipes (Left & Right)

• Installation Hardware Kit

• Protective Packaging

Installation

Direct bolt-on installation utilizing factory mounting locations.

No cutting or welding required.

Professional installation is highly recommended.

ECU tuning is recommended after installation to maximize performance and help prevent potential check engine lights.

Important Notes

Available in Catless and High-Flow Sport Catalytic configurations.

For motorsport or off-road use where permitted by local laws. Always verify your local emissions regulations before installation.

Why Choose OAO Performance

OAO designs and manufactures premium exhaust systems for Mercedes-AMG, BMW M, Audi RS, Porsche, Nissan GT-R, Ferrari, Lamborghini, Aston Martin, McLaren, and other world-class performance vehicles.

Every OAO exhaust component is developed through precision engineering, extensive vehicle testing, and motorsport-inspired design to deliver exceptional fitment, outstanding durability, and an exhilarating driving experience.

Upgrade your Mercedes-Benz ML550, GL550, GLS550, ML63 AMG, GL63 AMG, or GLS63 AMG with OAO Performance Downpipes and experience faster turbo response, improved exhaust flow, and the unmistakable sound of a high-performance twin-turbo V8.