Mercedes-AMG CLS53 C257: the return of the straight-six, the exhaust system guide
A four-door coupé with flowing lines, the CLS53 C257 benefits from Mercedes' return to a layout the brand had long set aside: the straight-six. Its 3.0-litre boosted M256 produces 435 hp and 520 Nm, sent to all four wheels by the 4MATIC+ drivetrain. A refined engine that the factory exhaust stifles to stay discreet every day. This guide presents the choices that let you tailor the ROG exhaust to this four-door coupé.
Written by ROG Motorsport · Updated
Your ROG exhaust for the Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+
From €3,390 in stainless steel, €4,140 in titanium
Configure my exhaust- Vehicles
- Mercedes-AMG CLS53 C257 3.0 inline-six M256 4MATIC+ (2019-2023)
- Engine
- M256 · 435 hp · 520 Nm
- Exhaust
- Valved cat-back, built for your VIN
- Material
- 304 stainless steel or titanium
- Front section
- Optional: catted downpipe with 200 or 100 cells, or decat
- Valves
- ROG remote, or factory control if your vehicle has it
- Lead time
- 20 working days from order confirmation to delivery
- Warranty
- 3 years, parts and workmanship
Closely related versions have their own guide: Mercedes-Benz CLS450 C257 3.0 inline-six turbo 4MATIC, Mercedes-Benz CLS350 C257 2.0 turbo, Mercedes-Benz GLE450 W167 3.0 inline-six turbo, Mercedes-AMG E53 W213 3.0 inline-six turbo.
The M256: the CLS53's boosted straight-six
The M256 is a 3.0-litre straight-six, boosted by a turbocharger assisted by an electric compressor that fills in the response time at low revs. In the CLS53 C257, it produces 435 hp and 520 Nm, sent to all four wheels by the 4MATIC+ drivetrain. The result is immediate, steady thrust, with the smooth running unique to straight-six engines.
A straight-six has a naturally fluid, even sound that lends itself perfectly to a valved exhaust. On the CLS53, the factory exhaust was tuned to preserve the serenity of a grand tourer. The ROG exhaust replaces it: with the valves closed, you keep that comfort; with the valves open, the M256 reveals a far sportier character. No work is needed on the engine or the ECU.
How the exhaust on your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+ is put together
An exhaust system is best understood in two parts. Here is what each one does, and what ROG replaces.
The cat-back is the complete exhaust system
It is everything you can see under your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+, from the outlet of the front section to the tips: pipes, silencer, valves. This is where our research and development is focused, and it is what shapes the sound. On its own, it changes the character of the car.
The front section, where the catalytic converter sits
On your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+, this is the downpipe, the pipe that leads away from the engine. It contains the factory catalytic converter: the second restriction in the exhaust, after the silencer. Replacing this part is optional: it frees up the flow, and an ECU remap is what turns that into power.
Your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+ in figures
On a modern car, an exhaust system first changes the voice, the breathing and the weight at the rear. Power, on the other hand, comes from an ECU remap.
Power
Torque
Published manufacturer and Stage 2 figures.
Our exhaust systems work perfectly with or without an ECU remap. On your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+, however, we recommend one at an approved tuning centre: it is what lets the engine deliver its full potential.
Configuring your exhaust, step by step
4 choices, in the same order as the product page configurator.
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Step 1 of 4: Material: stainless steel or titanium
For your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+, the exhaust costs €3,390 in stainless steel and €4,140 in titanium.
304 stainless steel
3 390 €
- Weight
- Baseline
- Sound
- Full and rounded
The benchmark for high-end exhausts: tough, corrosion-proof, with a full, rounded sound. The choice of most of our customers.
Titanium
4 140 €
- Weight
- Around 40% lighter
- Sound
- Metallic, crystal-clear
Around 40% lighter than stainless steel for the same design, with a more metallic sound that turns crystal-clear at high revs. Its finish ranges from brushed to blued tints.
Over time, both hold up: 304 stainless steel stands up to winter salt and damp, and titanium does not rust. Stainless steel or titanium: what really changes.
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Step 2 of 4: Front section: downpipe and catalytic converter
Optional: the downpipe on your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+, with its catalytic converter. Sound intensity is rated on our scale of 0 to 10, valves open; the factory exhaust scores 3.
Cat-back only
Included
7/10Factory emissions control
The factory catalytic converter stays in place. The starting point and, for many of our customers, more than enough.
200-cell sports catalytic converter
+800 €
8/10Road use and French MOT
Emissions control is still very much there, and flow improves noticeably. The choice for everyday driving.
100-cell sports catalytic converter
+800 €
9/10French MOT pass not guaranteed
Half as many cells: flow comes close to a decat and the sound gains real aggression at high revs.
Decat
+500 €
10/10Track use only
No emissions control: maximum flow, raw sound, the sharpest revving.
Sound intensity, on a scale of 0 to 10
- 10/10Decat downpipe + ROG cat-back
- 9/10100-cell sports catalytic converter + ROG cat-back
- 8/10200-cell sports catalytic converter + ROG cat-back
- 7/10ROG cat-back only, factory catalytic converter retained
- 3/10Factory exhaust, for comparison
Valves open. With the valves closed, every configuration becomes discreet again.
What about the engine warning light? A sports catalytic converter can trigger it: the oxygen sensor after the catalytic converter detects less cleaning than with the factory unit. It is not a fault. An ECU remap recalibrates the sensor, and a session with a diagnostic tool clears the fault code. With a decat, the warning light is almost certain without a remap. If it happens to you, call us and we will point you in the right direction. Passing the French MOT with a sports exhaust.
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Step 3 of 4: Valves: ROG remote or factory control
Two ways to control the valves on your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+.
ROG remote
A small control unit fits in the boot. Two buttons, open and closed: the valves respond at any moment, whatever the drive mode. Simple to fit, and we stay on hand throughout the installation.
Factory control
- Only for vehicles fitted with factory valves
- Controlled by the drive modes
If your vehicle is fitted with factory valves, the exhaust keeps their existing control. The drive modes decide, just as they did from the factory, with no added electronics.
On the motorway, with the valves closed, the gases pass through the silencer, designed for cruising: no drone at a steady speed. You open up when you feel like it, not when the motorway decides for you. More about exhaust drone.
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Step 4 of 4: Tips: the visual signature
Match the tips to the style of your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+, understated or bold. A particular finish in mind? Send us a photo and we will look at it together.
- Stainless steel
- Black
- Carbon
- Blued titanium
The ROG sound signature on the CLS53's M256
The M256 has a clearer, silkier voice than a V8, with a linear climb through the revs and a metallic tone reminiscent of the great six-cylinders of the past. On the CLS53, the factory exhaust keeps it in the background, true to the car's grand touring purpose.
With the ROG exhaust and the valves open, the CLS53 gains a broad, clean sound that accompanies every acceleration and every downshift. With the valves closed, it becomes once again the elegant, discreet four-door coupé, ideal for long journeys and understated arrivals.
From order to fitting
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Configuration
You choose your exhaust and enter your VIN, found in box E of your registration certificate.
-
Check
We check compatibility with your VIN before manufacturing begins.
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Manufacturing
Your exhaust is made to order, for your car.
-
Delivery
Free in Europe, insured to your door, tracked from dispatch.
-
Fitting
No welding or cutting: clamps and gaskets, around two hours on a lift.
20 working days from order confirmation to delivery
- Warranty
- 3 years, parts and workmanship, from the date of delivery
- Payment
- In instalments with Klarna
- Installation
- At the garage of your choice
What about the manufacturer's warranty on your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+? In Europe, a manufacturer cannot refuse warranty cover simply because a part from another brand has been fitted: it has to prove that the fault comes from that part. Our article on the manufacturer's warranty.
Our recommendations for your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+
-
Daily driving
3 390 €
- Stainless
- Cat-back only
- ROG remote
Your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+ stays easy to live with, the factory emissions control is retained, and you open the valves when you decide.
View this configuration -
Fast road
4 940 €
- Titanium
- 200-cell downpipe
- ECU remap
More sound, more breathing, and a car you can still present at the French MOT.
View this configuration -
Track
4 640 €
- Titanium
- Decat downpipe
- Stage 2
The most extreme configuration, for track use only.
View this configuration
And if you are still unsure, that is perfectly normal: it is exactly why we answer the phone.
Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+: your questions
How much power does an exhaust add on the Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+?
As standard, the Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+ produces 435 hp and 520 Nm. An exhaust system on its own mainly changes the sound, the breathing and the weight; power is gained with an ECU remap.
Stainless steel or titanium: which material for the Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+?
For the Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+, the ROG exhaust costs €3,390 in stainless steel and €4,140 in titanium. 304 stainless steel is tough, rounded in tone and the most popular choice; titanium is around 40% lighter for the same design, with a more metallic sound at high revs.
Do you need to replace the catalytic converter on the Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+?
No. On the Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+, the cat-back alone carries the valves and already transforms the sound. Replacing the downpipe is an option for going further: with a 200-cell sports catalytic converter for the road, 100-cell or decat for more radical use, with an ECU remap to turn it into power.
Does the Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+ pass the French MOT with a ROG exhaust?
With the cat-back only or the 200-cell sports catalytic converter, emissions control is retained: present the car with the valves closed. The 100-cell converter no longer guarantees a pass, and the decat fails the emissions test.
How is the ROG exhaust fitted on the Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+?
No welding or cutting, using clamps and gaskets. Allow two hours on average for a well-equipped mechanic. The exhaust is built for your VIN, which guarantees compatibility before it ships.
What price and lead time for a ROG exhaust on the Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+?
From €3,390 to €4,940 depending on the configuration. Allow 20 working days from order confirmation to delivery. Free delivery in Europe and a 3-year warranty.
Unsure about your configuration? Give us a call.
Stainless steel or titanium, cat-back only or the complete system: the right choice depends on how you use your Mercedes-AMG CLS53 C257 inline-six M256 4MATIC+. We take the time to talk it through before you order, with a reply within 24 hours. We are not here to sell to you over the phone: we help you choose, even if that means a cheaper option because it suits the way you drive.
RogMotorsport is a French brand built on one conviction: with an exhaust system, the support matters as much as the product. More than 500 exhaust systems fitted and a rating of 4.9 out of 5.
Further reading
- All Mercedes-AMG exhaust systems
- Mercedes-Benz CLS450 C257 3.0 inline-six turbo 4MATIC
- Mercedes-Benz CLS350 C257 2.0 turbo
- Mercedes-Benz GLE450 W167 3.0 inline-six turbo
- Exhaust diameter: bigger does not mean more powerful
- Passing the French MOT with a sports exhaust
- Stainless steel or titanium: what really changes
- The 22 brands we cover
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