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M177 Catless Downpipes for Mercedes-AMG C63 & C63S (W205) 2015–2023
M177 Catless Downpipes for Mercedes-AMG C63 & C63S (W205) 2015–2023
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These high-flow catless downpipes for W205 C63 / C63S AMG replace the factory catalytic converters, a major bottleneck on the M177 V8 BiTurbo platform. TIG-welded 304 stainless, 3.0″ OD with a 2.0mm wall, running the full 3.0″ diameter for nearly the entirety of the pipe rather than necking down after the flange. Once installed, you'll notice quicker turbo spool, sharper throttle response, and a much more aggressive AMG exhaust note. 590 WHP and 621 WTQ when paired with our M177 ECU tune. In US stock and shipped next business day.
Want thermal shielding? Select Heat Shielded in the selector above. High-temperature shielding cuts radiant heat coming off the pipe by up to 70–80%, holding under-hood temperatures down and protecting nearby wiring and sensors. It does not reduce backpressure — hotter gas in a fixed-diameter pipe carries a slightly higher frictional pressure drop. Worth it on a daily-driven or hot-climate car.
Real Sound Demo
Dyno Results — 590 WHP / 621 WTQ with downpipes and tune
Key Features & Benefits
- Direct Bolt-On — No cutting or fabrication required; installs in 2–3 hours. Professional installation is recommended
- TIG-Welded 304 Stainless Steel — Back-purged welds and machined flanges for leak-free, factory-spec connections. 3.0″ OD, 2.0mm wall, full 3.0″ diameter for nearly the entirety of the pipe
- Reduced Exhaust Backpressure — Allows the turbos to spool more efficiently and build boost faster under load
- Stronger Mid-Range Torque — with a Stage 2 calibration, the flow these free up lands where you actually drive
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 M177. 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 and heat side — worth doing together while the car is already on the lift.
- Intake: intake filter spacer kit, or the full 3″ dual intake kit
- Heat: front mount + auxiliary heat exchanger bundle
- Boost control: GFB DV+ diverter valve or VTA / BOV adapters
Compatibility
| Chassis | Years | Models |
|---|---|---|
| W205 Sedan | 2015–2021 | C63 AMG, C63 S AMG |
| C205 Coupe | 2016–2023 | C63 AMG, C63 S AMG |
| A205 Cabriolet | 2017–2023 | C63 AMG, C63 S AMG |
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
Do these require a tune?
They fit and run fine on a stock car, and the sharper throttle response is immediate. The power arrives with the calibration. A tune is highly recommended for maximum performance and to clear fault codes.
Will I get a check engine light?
Removing the catalytic converters will typically set a catalyst-efficiency code on an untuned car. A tune clears this properly — we do not recommend defeat devices.
Are they catless?
Yes — fully catless. Intended for off-road, track, and racing use only.
Will they fit my exact vehicle?
These fit the W205 Sedan (2015–2021), C205 Coupe (2016–2023), and A205 Cabriolet (2017–2023) C63 and C63 S AMG with the M177 4.0L BiTurbo V8. If your car is on that list, it bolts straight on with no cutting or fabrication.
How long does installation take?
Professional shops typically complete the install in 2–3 hours.
Off road use only. Not legal for use on emissions-controlled vehicles or public roads.
