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M278 Catless Downpipes – Mercedes S550 W222 Sedan (2014–2017) & C217 Coupe (2015–2017) 4.7L V8
M278 Catless Downpipes – Mercedes S550 W222 Sedan (2014–2017) & C217 Coupe (2015–2017) 4.7L V8
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High-flow catless downpipes for the Mercedes-Benz S550 with the M278 4.7L BiTurbo V8 — the W222 sedan (2014–2017) and the C217 coupe (2015–2017). They replace the factory catalytic converters to cut exhaust restriction, which brings faster turbo spool, sharper throttle response and stronger mid-range pull. Up to +160 hp and +300 lb-ft with ECU calibration and supporting modifications — those figures are with tuning; the downpipes alone do not produce them. Supplied as a complete left and right set as pictured; hardware and gaskets are not included unless shown in the photos.
Check your chassis, not just the badge
The S550 name spans two S-Class generations. 2011–2013 cars are the W221 — they run the same M278 engine but sit on a different chassis with different exhaust routing, and these will not fit them.
From the 2018 model year the V8 became the S560 with the 4.0L M176, which these also do not fit.
Key Features & Benefits
- Direct Replacement For The Factory Cats — removes the largest restriction in the exhaust path. Professional installation is recommended; inspect and replace gaskets and hardware as needed, and re-check for leaks after the initial heat cycles
- Improved Exhaust Flow — lower backpressure lets the turbos operate more efficiently and build boost sooner
- Sharper Response — faster spool and stronger mid-range pull, which is where an S-Class actually spends its time
- More Aggressive Sound — increased volume and a deeper tone than the factory converters, varying with the rest of your exhaust setup
Complete the Build
A catless setup will typically set a check-engine light without proper calibration. The tune is what turns the hardware loose — it lets the ECU use the extra flow and clears the fault codes properly.
What Else Owners Add At The Same Time
Downpipes free up the exhaust side. These address the intake side and under-hood heat — worth doing together while the car is already on the lift.
- Intake: M278 intake filter spacer kit
- Heat: M278 turbo blankets — keeps radiant heat off surrounding components once the cats are gone
- Drive accessories: M278 billet aluminum pulley set
Compatibility
| Chassis | Years | Models |
|---|---|---|
| W222 Sedan | 2014–2017 | S550 |
| C217 Coupe | 2015–2017 | S550 |
All fitments above use the M278 4.7L BiTurbo V8. If your car is on that list, these bolt straight on with no cutting or fabrication.
Warranty, Shipping & Returns
- 12-month structural warranty — covers welds, flanges, and structural integrity under normal street use
- Free U.S. shipping with tracking, shipped next business day from US stock
- 30-day returns — unused and uninstalled, in original packaging. See full return policy →
Frequently Asked Questions
Will these fit my S550?
Yes for the W222 sedan (2014–2017) and the C217 coupe (2015–2017) with the M278 4.7L BiTurbo V8. They do not fit the 2011–2013 W221 S550, and they do not fit the 2018-and-later S560 with the M176 4.0L V8.
My 2012 S550 has the same M278 engine — why doesn't this fit?
The engine is the same, but the car isn't. 2011–2013 S550 models are the previous-generation W221 chassis, which routes its exhaust differently. The W222 replaced it for the 2014 model year, and the C217 coupe arrived for 2015. Downpipes are chassis-specific, not just engine-specific.
Do I need a tune?
Strongly recommended. A catless setup will usually set a check-engine light without proper calibration, and the tune is what unlocks the flow the hardware now allows.
Will I get a check engine light?
Likely, on an untuned car. Removing the cats means the downstream O₂ sensors read differently than the ECU expects. A calibration resolves it properly — we do not recommend defeat devices.
What performance gains can I expect?
Faster turbo spool, sharper throttle response and stronger mid-range torque on their own. Paired with ECU calibration and supporting modifications, up to +160 hp / +300 lb-ft is achievable.
Are these loud?
They produce a deeper, more aggressive note than the factory catalytic converters. Sound level depends on your full exhaust setup.
Is there a warranty?
Yes — a 12-month structural warranty, with guaranteed fitment on every model listed above.
Off-road use only. Not legal for use on emissions-controlled vehicles or public roads.
