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M274 Catless Downpipe for Mercedes C300 / E300 / GLC300 (W205 / W213 / X253) 2015–2021
M274 Catless Downpipe for Mercedes C300 / E300 / GLC300 (W205 / W213 / X253) 2015–2021
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The factory catalytic converter sits directly after the turbo on the M274 2.0L turbo and is the single largest restriction in the system. This high-flow catless downpipe removes that bottleneck for noticeably quicker spool, sharper throttle response, stronger mid-range torque and a more aggressive turbo sound — while staying daily-drivable. 2.75″ diameter, direct bolt-on, fitting the C300 (W205 / C205 / A205), E300 (W213) and GLC300 (X253) in both RWD and 4MATIC.
Real Sound & Spool
Key Features & Benefits
- 2.75″ Diameter — sized to what the M274 actually flows. On a 2.0L four, exhaust gas velocity is what carries mid-range torque and turbo response, and a pipe sized past the engine's flow gives that away
- Quicker Spool, Sharper Throttle — removing the restriction immediately after the turbo is the largest single response gain available on this platform
- Stronger Mid-Range Torque — the part of the powerband a C300 actually lives in, which is why the car feels quicker in everyday driving rather than only at the top end
- Direct Bolt-On — no cutting or fabrication. Professional installation is recommended
Complete the Stage 2 Build
The downpipe alone wakes the car up. The tune is what turns it loose — it lets the ECU take advantage of the extra flow, and it clears the fault code the catless design will otherwise set.
Downpipe + Stage 2 tune bundle →
Prefer to pick parts separately? Custom M274 ECU tune · JB4 piggyback tuner
What Else Owners Add At The Same Time
The downpipe frees up the exhaust side. Owners running a tune alongside it typically address boost control next, then the brakes to match the extra pace.
- Boost control: GFB DV+ T9358 diverter valve — the factory diverter is a known weak point once boost climbs
- Braking: stainless braided brake lines — firmer pedal to match the extra pace
Compatibility
| Chassis | Years | Models |
|---|---|---|
| W205 / C205 / A205 | 2015–2021 | C300 |
| W213 | 2017–2020 | E300 |
| X253 | 2016–2019 | GLC300 |
All fitments above use the M274 2.0L turbo. RWD and 4MATIC models are both supported. If your car is on that list, this bolts 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 in original packaging. See full return policy →
Frequently Asked Questions
Why 2.75″ and not 3 inches?
A downpipe sized past what the engine actually flows drops exhaust gas velocity, and velocity is what carries mid-range torque and turbo response. Each downpipe is sized to the engine it fits rather than to one number applied across every platform. The M274 is a 2.0L four — 2.75″ is matched to it, and going wider would cost the low-end response this mod is bought for in the first place.
Will I get a check engine light?
Likely, on an untuned car. Removing the cat means the downstream O₂ sensor reads differently than the ECU expects. A tune resolves it properly — we do not recommend defeat devices.
Do I need a tune?
The car will run without one, but tuning is strongly recommended — it is what lets the ECU use the extra flow, and it clears the fault code a catless setup will otherwise set.
Does this fit 4MATIC cars?
Yes. Both rear-wheel-drive and 4MATIC versions of the models listed above are supported.
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.
