Mercedes-Benz CLS350 C257: elegance finds its voice, the exhaust system guide
The CLS350 C257 carries on the idea that made the CLS a success: a saloon with the looks of a coupé, elegant and comfortable. Under the bonnet sits a 2.0-litre turbocharged four-cylinder with 299 hp, which the factory exhaust renders almost inaudible. The aim of this guide: to help you configure a ROG exhaust that gives the engine a presence in keeping with the style of the CLS, without sacrificing any of its refinement.
Written by ROG Motorsport · Updated
Your ROG exhaust for the Mercedes-Benz CLS350 C257
From €2,490 in stainless steel, €2,990 in titanium
Configure my exhaust- Vehicles
- Mercedes-Benz CLS350 C257 2.0 turbo (2018-2023)
- Engine
- M264 / M274 · 299 hp · 400 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-AMG CLS53 C257 3.0 inline-six M256 4MATIC+.
The M264: the turbocharged four-cylinder of the CLS350 C257
The CLS350 C257 gets the M264, a 2.0-litre turbocharged inline four-cylinder. It produces 299 hp and 400 Nm, with early torque that gives the car strong acceleration despite the size of a large saloon. It is a modern, flexible engine that favours efficiency over expression, and it suits the grand touring character of the CLS well.
On a turbocharged four-cylinder, the exhaust shapes much of how the engine is perceived. The factory system on the CLS350 was designed to make it almost imperceptible, to the point of stripping it of any personality. The valved ROG exhaust replaces it without touching the engine or the ECU: you keep muted running every day, and the four-cylinder gains character as soon as you open the valves.
How the exhaust on your Mercedes-Benz CLS350 C257 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-Benz CLS350 C257, from the outlet of the front section to the tips: pipes, silencer, valves. Routing, silencer, valves: this is where the sound is shaped, and where we focus our research and development.
The front section, where the catalytic converter sits
On your Mercedes-Benz CLS350 C257, this is the downpipe, the pipe that leads away from the turbo. It contains the factory catalytic converter: the second restriction in the exhaust, after the silencer. Changing this part remains a choice: it pays off mainly with an ECU remap, which turns the freed-up flow into power.
Your Mercedes-Benz CLS350 C257 in figures
What an exhaust changes straight away is the sound, the engine's breathing and the weight at the rear. For more power, add an ECU remap.
Power
Torque
Published factory and Stage 2 figures.
With or without an ECU remap, the exhaust fits and works. But it is an ECU remap at an approved tuning centre that truly unleashes your Mercedes-Benz CLS350 C257, and that is what we recommend.
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-Benz CLS350 C257, the exhaust costs €2,490 in stainless steel and €2,990 in titanium.
304 stainless steel
2 490 €
- Weight
- Baseline
- Sound
- Full and rounded
Durable, corrosion-resistant, with a rounded, full sound: the most popular option.
Titanium
2 990 €
- Weight
- Around 40% lighter
- Sound
- Metallic, crystal-clear
For the same design, it weighs around 40% less than stainless steel. A more metallic note at high revs and a look all of its own, from brushed to blued.
Both materials age well: 304 stainless steel copes with winter and salt, 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-Benz CLS350 C257, with its catalytic converter. Sound rating out of 10, valves open: the factory exhaust sits at 3.
Cat-back only
Included
7/10Factory emissions control
Nothing changes at the front: the cat-back alone is already enough to change the car.
200-cell sports catalytic converter
+660 €
8/10Road use and French MOT
The everyday compromise: emissions control is still there, and breathing improves noticeably.
100-cell sports catalytic converter
+660 €
9/10French MOT pass not guaranteed
One step further: more flow, a more aggressive sound, reduced emissions control.
Decat
+420 €
10/10Track use only
Everything unleashed: maximum flow and unrestrained sound, for the track.
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? It can appear with a sports catalytic converter: the downstream oxygen sensor reads a different level of cleaning from the factory unit. It is not an engine fault, and it is dealt with by an ECU remap or a diagnostic tool. With a decat, an ECU remap becomes necessary. 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-Benz CLS350 C257.
ROG remote
The simplest solution: a control unit in the boot and a remote, open or closed at the press of a button, whatever mode you are in. A question while fitting? We will get back to you.
Factory control
- Only for vehicles fitted with factory valves
- Controlled by the drive modes
Does your vehicle have factory valves? The exhaust keeps their existing control: the drive modes operate the valves, as before, with no added electronics.
On a long journey, what matters is the absence of drone at a steady speed. With the valves closed, the exhaust keeps the cabin calm; the show is still there whenever you ask for it. 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-Benz CLS350 C257, 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 CLS350 C257
A modern turbocharged four-cylinder has more character than you might suspect, with a muted note at low revs and a livelier edge under acceleration. The factory exhaust on the CLS350 erases all of this and leaves only a neutral whisper, at odds with the car's sporty design.
With the valves open, the ROG exhaust gives the four-cylinder a deeper, more substantial tone that accompanies acceleration without becoming intrusive. With the valves closed, the CLS regains its elegant factory silence, ideal for long journeys and business meetings.
From order to fitting
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Configuration
You choose the options for your Mercedes-Benz CLS350 C257 and enter its VIN, found in box E of the registration certificate.
-
Check
We confirm compatibility with your car before we build it.
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Manufacturing
Made to order, for your Mercedes-Benz CLS350 C257.
-
Delivery
Free, insured delivery, with tracking sent on dispatch.
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Fitting
Clamps and gaskets, no welding: two hours on average at the garage of your choice.
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? In Europe, fitting a part from another brand is not enough on its own to void it; the manufacturer has to prove the link between that part and the fault. Our article on the manufacturer's warranty.
Our recommendations for your Mercedes-Benz CLS350 C257
-
Daily driving
2 490 €
- Stainless
- Cat-back only
- ROG remote
Your Mercedes-Benz CLS350 C257 stays easy to live with, the factory emissions control is retained, and you open the valves when you decide.
View this configuration -
Fast road
3 650 €
- Titanium
- 200-cell downpipe
- ECU remap
For great roads: more voice and more response, while staying road-friendly.
View this configuration -
Track
3 410 €
- Titanium
- Decat downpipe
- Stage 2
The most extreme configuration, for track use only.
View this configuration
These profiles are starting points. The right choice is often made in five minutes on the phone.
Mercedes-Benz CLS350 C257: your questions
How much power does an exhaust add on the Mercedes-Benz CLS350 C257?
As standard, the Mercedes-Benz CLS350 C257 produces 299 hp and 400 Nm. Without a remap, the exhaust transforms the voice and lightens the rear; it is the ECU remap that increases power.
Stainless steel or titanium: which material for the Mercedes-Benz CLS350 C257?
For the Mercedes-Benz CLS350 C257, the ROG exhaust costs €2,490 in stainless steel and €2,990 in titanium. Choose stainless steel for value for money and a rounded sound, titanium to save around 40% in weight and get a clearer tone.
Do you need to replace the catalytic converter on the Mercedes-Benz CLS350 C257?
No, the cat-back alone already does most of the work on the Mercedes-Benz CLS350 C257. The downpipe option is for those tuning the engine: 200 cells to stay road-friendly, 100 cells or decat for the track.
Does the Mercedes-Benz CLS350 C257 pass the French MOT with a ROG exhaust?
The cat-back only and the 200-cell sports catalytic converter both keep emissions control: that is the configuration to present, with the valves closed. The 100-cell converter makes a pass uncertain, and the decat fails the emissions test on the Mercedes-Benz CLS350 C257.
How is the ROG exhaust fitted on the Mercedes-Benz CLS350 C257?
Fitting needs no welding or cutting and takes two hours on average on a lift. We check compatibility with the VIN of your Mercedes-Benz CLS350 C257 before manufacturing.
What price and lead time for a ROG exhaust on the Mercedes-Benz CLS350 C257?
From €2,490 to €3,650 depending on the configuration. Allow 20 working days from order confirmation to delivery. Free delivery in Europe, 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-Benz CLS350 C257. 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.
Behind every ROG exhaust is a French team you can actually reach, who know the cars they talk about. More than 500 exhaust systems fitted and a rating of 4.9 out of 5.
Further reading
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