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M157 Catless Downpipes – Mercedes E63 AMG W212 & CLS63 AMG C218 (2012–2013) RWD 5.5L V8
M157 Catless Downpipes – Mercedes E63 AMG W212 & CLS63 AMG C218 (2012–2013) RWD 5.5L V8
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High-flow catless downpipes for the 2012–2013 Mercedes-AMG E63 (W212 / S212) and CLS63 (C218 / X218) with the M157 5.5L V8 BiTurbo, rear-wheel drive. These are the primary downpipes — they bolt straight to the turbo outlets and remove the biggest restriction in the system, quickening spool and deepening the AMG tone. Back-purged TIG-welded 304 stainless steel, 2.75″ primaries tapering to 2.5″, direct bolt-on to the OEM mounting points, roughly 10–15 lbs lighter than the factory assemblies. In US stock and shipped next business day.
2014 or newer, or a 4MATIC car? US-spec E63 and CLS63 moved to 4MATIC for 2014, and the all-wheel-drive cars use different routing — see the 4MATIC version →
Driving an S63, CL63, SL63, ML63, GL63 or G63? Same M157 engine, but downpipes are chassis-specific and these will not fit — S63 W222 downpipes →
Key Features & Benefits
- 2.75″ Primaries Tapering To 2.5″ — sized to what the M157 actually flows. The taper accelerates exhaust gas through the section rather than letting it stall in an oversized pipe, which is what protects mid-range torque and turbo response
- TIG-Welded 304 Stainless Steel — back-purged welds throughout, bolting to the factory mounting points, and roughly 10–15 lbs lighter than the OEM assemblies
- Direct Bolt-On — no cutting or fabrication required; installs in 2–3 hours. Professional installation is recommended
- Primary Cat Removal Where It Counts — the primary catalytic converters are the single largest restriction on a stock M157. Removing them supports quicker turbo spool and a deeper AMG tone under load without excessive drone
Will downpipes alone add power?
A little. Nothing like the numbers you'll see advertised.
Your ECU targets a set boost level and holds it with the wastegate. Lower the backpressure and it doesn't raise that target — it just reaches the same number with the gate cracked further open. Fuel is metered to measured airmass to hold a target air-fuel ratio, so if airmass doesn't change, fuelling doesn't change, and neither does power. You don't make more power without burning more fuel, and the ECU decides how much fuel it burns.
There are two places you do gain on a stock calibration. At the top of the pull the wastegate is already shut and the turbos are at their limit — there's no regulation left, so less restriction means genuinely more airflow and the ECU fuels it. And lower exhaust gas temperatures mean less timing pulled on a knock-limited engine. Together that's a handful of horsepower, mostly at high RPM.
What you'll feel is much bigger than what you'll measure. Boost arrives sooner, so the car is quicker to respond and quicker between gears — which is why owners often report large gains from downpipes alone. That's turbo response, not output.
The flow becomes power when the calibration does. A tune raises the boost target and fuels it. Any large figure quoted for "downpipes alone" was almost certainly measured on a tuned car — a real number with a misleading label.
Complete the Stage 2 Build
These downpipes are the hardware half of a Stage 2 M157. The tune is what turns them loose — it lets the ECU take advantage of the extra flow, and it clears the check-engine light the catless design will otherwise set.
What Else Owners Add At The Same Time
Downpipes free up the exhaust side. These address the intake side, the install itself, and the section further downstream — worth doing together while the car is already on the lift.
- Intake: M157 intake spacer kit and K&N high-flow air filters
- Install: 24″ O₂ sensor extension harness — catless pipes reposition the sensor bungs and the factory leads often will not reach comfortably
- Further downstream: Supersprint secondary downpipes (CLS63 C218) — the secondary cats are a separate restriction and can be removed alongside these
Compatibility
| Chassis | Years | Models |
|---|---|---|
| W212 Sedan / S212 Wagon — RWD | 2012–2013 | E63 AMG |
| C218 Coupe / X218 Shooting Brake — RWD | 2012–2013 | CLS63 AMG |
All fitments above use the M157 5.5L V8 BiTurbo. 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 in original packaging. See full return policy →
Frequently Asked Questions
Why 2.75″ and not larger?
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. On the RWD M157 that means 2.75″ primaries tapering to 2.5″ — the taper is deliberate, accelerating gas through the section instead of letting it stall in an oversized pipe.
Will these work on the stock tune?
The car will run without calibration, but ECU tuning is recommended for best drivability and performance.
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.
Do I need the O₂ sensor extension harness?
Often, yes. A catless downpipe repositions the sensor bungs relative to the factory pipe, and the original leads may not reach comfortably. A 24″ extension avoids stretching or splicing the harness — a small part that prevents a stalled install.
What's the difference between these and the secondary downpipes?
These are the primary downpipes — they bolt directly to the turbo outlets, where the biggest restriction sits. The secondary downpipes replace the second set of catalytic converters further downstream. They address different sections of the exhaust and can be run together.
Are these street legal?
No. These delete the primary catalytic converter. They hold no CARB Executive Order, are not 50-state legal, and are not legal to install on a vehicle registered or operated on public roads in the United States. Sold for closed-course competition and off-road use only — see the emissions notice at the top of this page.
Will they fit my exact vehicle?
These fit rear-wheel-drive 2012–2013 E63 AMG (W212 / S212) and CLS63 AMG (C218 / X218) with the M157 5.5L V8 BiTurbo. US-spec 2014 and newer cars are 4MATIC and need the all-wheel-drive version linked above.
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.
