BenzUnited Parts
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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Off-road and competition use only. May not comply with local emissions regulations. Buyer is responsible for compliance with local laws.
Reduce exhaust restriction and improve turbo response with a catless downpipe set built for the Mercedes-Benz S550 with the M278 BiTurbo V8 — the W222 sedan (2014–2017) and the C217 coupe (2015–2017). Designed to increase exhaust flow for faster spool and stronger mid-range response, especially when paired with proper ECU calibration.
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.
What's Included
Complete left and right downpipe set as pictured. Hardware and gaskets are not included unless shown in the photos.
Why Upgrade the Factory Downpipes?
- +118 hp / +190 lb-ft — with these downpipes and ECU calibration
- Improved exhaust flow — reduces backpressure for more efficient turbo operation
- Sharper response — faster spool and stronger mid-range pull
- More aggressive sound — increased volume and a deeper tone, varying by 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.
Fitment
| Years | Model | Chassis | Engine |
|---|---|---|---|
| 2014–2017 | S550 Sedan | W222 | M278 4.7L BiTurbo V8 |
| 2015–2017 | S550 Coupe | C217 | M278 4.7L BiTurbo V8 |
Confirm your chassis code and engine before ordering. Not sure? Send us your VIN and we'll verify before you order.
Installation Notes
- Professional installation recommended
- Inspect and replace gaskets and hardware as needed during installation
- Re-check for leaks after the initial heat cycles
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, and +118 hp / +190 lb-ft once paired with ECU calibration.
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.
Buy With Confidence
- 12-month structural warranty with guaranteed fitment on listed models
- Free U.S. shipping with tracking on every order
- 30-day returns on unused, uninstalled items in original packaging — installed exhaust components are not eligible
- Fitment confirmed before you buy — send your VIN and we'll verify before you order
- Real support — questions before or after purchase go straight to us, not a call center
Confirm fitment or ask a question →
BenzUnited Parts • M278 S550 Downpipes • 12-Month Warranty • Ships Fast
