BMW M135i F20: waking up the N55, the complete exhaust system guide
The M135i F20 remains one of the best sources of driving pleasure per litre of its generation: N55 straight-six, rear-wheel drive, compact format. Enthusiasts are actively seeking it out today. Its N55 has the deep voice typical of BMW sixes, and all it asks for is an exhaust worthy of the name to let it be heard. For your BMW M135i N55, this guide sets out what each choice changes: material, front section, sound, valves and fitting.
Written by ROG Motorsport · Updated
Your ROG exhaust for the BMW M135i N55
From €2,490 in stainless steel, €2,990 in titanium
Configure my exhaust- Vehicles
- BMW M135i N55 3.0T (2013-2016)
- Engine
- N55 · 320 to 326 hp · 450 Nm, depending on the version
- 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: BMW 335i N55 E90 / E92 / E93 3.0T, BMW 535i N55 F10 3.0T, BMW 640i N55 F06 Gran Coupé 3.0T, BMW M2 N55 F87 3.0T.
The N55: the endearing single-turbo that the factory exhaust silences
The 3.0L N55 is the single-turbo straight-six that preceded the B58: linear power delivery, a naturally deep and mechanical sound, and robustness proven across hundreds of thousands of units. It is an engine with genuine character, highly prized for tuning. On your M135i F20, the factory exhaust, sized for discretion, holds back the essentials: the deep tone, the metallic harmonics and the crackles on the overrun.
The ROG exhaust removes these unnecessary filters. The N55 gets its deep voice back, with valves that give you the factory discretion on demand.
How the exhaust on your BMW M135i N55 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 BMW M135i N55, from the outlet of the front section to the tips: pipes, silencers, 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 BMW M135i N55, it is the downpipe, the pipe leading from the turbo. 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.
The figures for your BMW M135i N55
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 factory and Stage 2 figures. Factory figures vary by version; Stage 2 figures published for the 326 hp version.
Our exhaust systems work perfectly with or without an ECU remap. On your BMW M135i N55, however, we recommend having one done at an approved tuning centre: that is what lets the engine reach its full potential.
To be transparent: the exhaust alone brings a moderate gain, linked to the reduced back pressure, which is especially noticeable in throttle response on a single-turbo engine. The real unlocking comes with Stage 2, the exhaust plus an ECU remap at an approved tuning centre. The N55 has been proven in tuning for more than ten years: the figures above stay well within its comfort zone.
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 BMW M135i N55, the exhaust costs €2,490 in stainless steel and €2,990 in titanium.
304 stainless steel
2 490 €
- 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
2 990 €
- 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 BMW M135i N55, 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
+780 €
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
+780 €
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
+520 €
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 BMW M135i N55.
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 BMW M135i N55, 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
- M Performance style carbon
The ROG sound signature on the N55
The N55 has a deeper, more mechanical timbre than the latest straight-sixes. Our exhaust brings it to the fore: an assertive presence from idle, a raw, full climb through the revs, and crisp crackles on the overrun with the valves open. With the valves closed, the car regains a discretion that is perfectly suited to everyday use.
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.
-
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 BMW M135i N55? 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 was caused by that part. Our article on the manufacturer's warranty.
Our recommendations for your BMW M135i N55
-
Daily driving
2 490 €
- Stainless
- Cat-back only
- ROG remote
Your BMW M135i N55 stays easy to live with, the factory emissions control is retained, and you open the valves whenever you decide.
View this configuration -
Fast road
3 770 €
- 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
3 510 €
- 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.
BMW M135i N55: your questions
How much power does an exhaust system add to the BMW M135i N55?
As standard, the BMW M135i N55 produces from 320 to 326 hp and 450 Nm, depending on the version. An exhaust system on its own mainly changes the sound, the breathing and the weight; power is gained with an ECU remap. With a Stage 2 build, the published figures for the 326 hp version reach 399 hp and 546 Nm.
Stainless steel or titanium: which material for the BMW M135i N55?
For the BMW M135i N55, the ROG exhaust costs €2,490 in stainless steel and €2,990 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 BMW M135i N55?
No. On the BMW M135i N55, 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.
Will the BMW M135i N55 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 to the BMW M135i N55?
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 does a ROG exhaust cost for the BMW M135i N55, and how long does it take?
From €2,490 to €3,770 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 drive and on your BMW M135i N55. 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
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