Best valved exhaust for BMW M135i F20 / F21

Your vehicle.

All our exhausts for this generation, version by version, are brought together on one page: BMW 1 Series F20 / F21 Valved Exhaust.

The M135i brought together what no other compact of its time offered: a turbocharged inline six-cylinder and rear-wheel drive, in a 1 Series of ordinary size. Here is what you need to know about yours, from its versions to its voice, before choosing its exhaust.

Body styles

Five-door F20 and three-door F21

Launch

From 2012; facelift in 2015; replaced by the M140i in 2016

Years covered by the product page

2013 to 2016; a 2012 M135i is checked against the VIN

Engine

N55, 2,979 cc in inline six-cylinder, boosted by a twin-scroll turbo

Factory output

320 hp (235 kW), 326 hp (240 kW) since the facelift; 450 Nm in both cases

Transmission

Six-speed manual or eight-speed automatic

Drivetrain

Rear-wheel drive, or xDrive as an option

A six-cylinder 1 Series

BMW showed the M135i as a concept at the Geneva show in March 2012, then put it on sale the same year, as the five-door F20 and the three-door F21. It crowned the second-generation 1 Series range, with a presentation, equipment and chassis settings of its own.

The 2015 facelift redesigned its headlights and lights, and added a few horsepower. In 2016, the B58-engined M140i took its place. The M135i thus remains the only 1 Series with an N55 engine, and a rarity: the next 1 Series, the F40, abandoned rear-wheel drive, and its sportiest version makes do with a four-cylinder.

As for the body, the three-door F21 appeals with its compact coupé look, the five-door F20 with its rear doors, more practical day to day. Under the body, both share the same mechanics: same N55, same transmissions, same Rog exhaust, with the same options of material, sound and tips.

320 hp, then 326 hp

First phase: 235 kW, or 320 hp, reached at 5,800 rpm, with 450 Nm between 1,300 and 4,500 rpm. The 2015 facelift adds six horsepower, 326 hp (240 kW), without touching the torque. The gap is slim, but it helps date a car, and the Rog product page accepts both.

Our product page is intended for M135i models from 2013 to 2016. If yours is among the first, delivered in 2012, we check its VIN before any order and reply in writing. The M140i, which succeeds it with a different engine, has its own guide.

320 hp version from the factory

326 hp version from the factory

Stage 2: published figures with the front section and an ECU remap carried out by a tuner.

Manual, automatic, rear-wheel drive or xDrive

Two transmissions were available: six-speed manual or eight-speed automatic. Rear-wheel drive was standard, xDrive optional. The data sheets give 0 to 100 km/h in 4.9 seconds for the rear-wheel-drive automatic, and in 4.7 seconds for the xDrive automatic.

For the rear exhaust, none of these variants changes the product page. Manual or automatic, rear-wheel drive or xDrive, three or five doors: the same Rog exhaust fits, and your VIN confirms compatibility before manufacture.

The N55 in longitudinal position

Under the M135i's hood, the N55 lines up six cylinders for 2,979 cc, with direct injection and a single twin-scroll turbo: cylinders 1 to 3 feed one inlet, cylinders 4 to 6 the other. The turbo thus responds quickly, from low revs, which gives the compact strong pick-up across the whole usable range.

The N55 is found, in the same period, in the 535i F10, the 640i or the first-phase M2. In the M135i, it is mounted lengthways, as in the big BMWs, so that with rear-wheel drive the front wheels only have to steer. Its turbo leads to a downpipe fitted with the catalytic converter: the front section. Behind it, the cat-back reaches the rear under the floor.

A six-cylinder in a compact

With its six inline cylinders, the N55 runs smoother than few engines: at idle, a deep growl; at the top of the rev counter, a more metallic song. In a car as short as a 1 Series, it is an unusual voice, closer to that of a large sedan than to that of a sporty compact.

With the exhaust open, the M135i's N55 climbs through the revs with a full, rasping grain, and crackles openly when you lift off, especially when the automatic transmission downshifts. On the product page, the character is chosen free of charge: a straight pipe for this unfiltered grain, or a resonator to give it a rounder and slightly softer voice, still sporty.

A voice kept on a leash

The M135i's factory exhaust was sized for discretion: the car had to remain liveable day to day and respect noise limits, despite its 320 hp. The result, from outside, is a compact that passes almost unnoticed, even when the N55 is working hard. You sense the six-cylinder more than you hear it.

With valves, this compromise disappears. Closed, they route the gases through every chamber of the muffler: the M135i stays close to its standard volume for leaving a sleepy neighbourhood or for hours of highway. Open, they give the gases a direct passage, and the six-cylinder can be heard as it is.

The driving modes and the Rog remote

The M135i offers several driving settings, from Eco Pro, oriented to consumption, to Comfort, Sport and Sport Plus, which sharpen the responses. With the Rog exhaust, the valves no longer depend on these modes: they are fitted to the exhaust and controlled by a two-button remote, with a small control unit housed in the trunk.

Open, they stay open, even in Eco Pro; closed, they stay closed, even in Sport Plus. You decide the car's voice at the moment you want, without going through menus: discreet when crossing a village, full on a clear country road or on a track day.

Two outlets, tips and material

At the rear, the M135i carries two large round outlets, one at each corner of the bumper. Three Rog tip finishes are included: chrome, gloss black, blued titanium. As an option, the carbon tips with the M logo come in forged, black or carbon and titanium. And if you prefer, the exhaust can arrive without tips.

304 stainless steel gives the six-cylinder a full note and fears neither winter nor salt. About 40% lighter for the same layout, titanium brightens the voice in the revs and is tinted brushed, gold or purple, with no price difference.

Front section and power

The product page adds, as the "Manifold" option, the N55's downpipe: with a 200- or 100-cell sport catalytic converter, or catalyst-free for the track. An M135i that runs summer and winter keeps its emissions control with the 200-cell.

With the factory engine software kept, the car stays at 320 or 326 hp: the exhaust transforms the sound, the power does not move. More horsepower requires the downpipe and a remap, a tuner's business. We make the exhaust from your VIN; your garage then fits it, clamps and gaskets are enough, without welding or cutting.

Configure your exhaust.

How the exhaust is put together

On the M135i, three or five doors, our cat-back begins at the end of the downpipe and reaches the two rear outlets running along the floor: pipes, muffler, valves. The front section is limited to this N55 downpipe, catalytic converter included: on the product page, it is added as an option under the label "Manifold".

Each choice explained in detail, from sound to material: How to configure your exhaust.

Three recommended configurations.

• Every day

  • Stainless steel
  • No manifold
  • Straight pipe
  • Rog remote

  For an M135i used every day: the factory downpipe stays in place, the six-cylinder regains its grain, and one button quietens it before you reach home.

  View this configuration

• Winding roads

  • Brushed titanium
  • 200-cell sports catalytic converter
  • Resonator

  For a rear-wheel-drive car that loves bends: the N55 gains presence and breath, with a rounder and slightly softer voice, and emissions control stays in service.

  View this configuration

• Track

  • Titanium
  • Catalyst-free manifold
  • Carbon tips with the M logo

  For a tuned M135i that runs on the circuit: the freest flow after the turbo, the lightest exhaust and open valves from the first lap to the last.

  View this configuration

From order to fitting.

VIN, manufacture, delivery, fitting and warranty, step by step

Questions.

Further reading.

• All our exhausts for BMW 1 Series F20 and F21
• Guide to the BMW M140i B58 F20 / F21
• Guide to the BMW M2 N55 F87
• Guide to the BMW 640i N55 F06 / F12 / F13