BenzUnited Parts
M178 Catless Downpipes – Mercedes-AMG GT / GT S / GT C / GT R (R190) 4.0L V8 BiTurbo
M178 Catless Downpipes – Mercedes-AMG GT / GT S / GT C / GT R (R190) 4.0L V8 BiTurbo
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These high-flow catless downpipes for the Mercedes-AMG GT replace the factory catalytic converters, a major bottleneck on the M178 4.0L V8 BiTurbo. TIG-welded 304 stainless, 3.0″ OD with a 2.0mm wall and 8.5mm high-temperature TIG welds at the flanges. Once installed, you'll notice quicker turbo spool, sharper throttle response, and a harder-edged AMG note under load. Direct bolt-on, no cutting. In US stock and shipped next business day.
These fit the R190 AMG GT, the two-seat car built from 2015 to 2021. Every variant is covered — base GT through Black Series, coupé and roadster alike.
Real Sound Demo
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 — 8.5mm high-temperature TIG welds and machined flanges for leak-free, factory-spec connections. 3.0″ OD with a 2.0mm wall
- 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
Complete the Stage 2 Build
These downpipes are the hardware half of a Stage 2 M178. 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.
Compatibility
| Chassis | Years | Models |
|---|---|---|
| R190 | 2015–2021 | AMG GT |
| R190 | 2015–2021 | AMG GT S |
| R190 | 2018–2021 | AMG GT C, AMG GT C Roadster |
| R190 | 2018–2021 | AMG GT Roadster |
| R190 | 2018–2021 | AMG GT R, AMG GT R Pro |
| R190 | 2021 | AMG GT Black Series |
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?
Likely, on a stock car. Removing the cats means the downstream O₂ sensors read differently than the ECU expects. 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?
Check the table above. These fit the R190 AMG GT — every variant of it, from the base GT through GT S, GT C, GT R, GT R Pro and Black Series, coupé and roadster, 2015 to 2021. Fitment is decided by chassis, not by engine. If your car is on that list, it bolts straight on with no cutting or fabrication.
Does the Black Series use the same downpipes?
Yes. The Black Series runs a different top end, but the chassis and the downpipe mounting are shared with the rest of the R190 range, so this set fits it.
How long does installation take?
Professional shops typically complete the install in 2–3 hours.
Is there a warranty?
Yes — a 12-month structural warranty, with guaranteed fitment on every model listed above.
