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BMW 135i / 335i N54Stage 1 to Stage 4 tuning guide

The N54 was what BMW called the world's first straight-six with twin-turbo technology (BMW UK). In the US the 335i was rated at 300 hp and 300 lb-ft from 1,400 to 5,000 rpm, with a six-speed manual or automatic (BMW USA), and the 135i that followed had the same figures (BMW USA); in Britain it was 306 hp and 400 Nm (BMW UK). The 2011 335i coupé and convertible moved to the single-turbo N55 (BMW USA), so this guide covers the 2007–2010 cars.

Years
2007–2010
Engine
3.0 twin-turbo inline-six N54
Gearbox
6-speed manual or 6-speed automatic
Stock power
US 300 hp / 300 lb-ft; UK 306 hp / 400 Nm

Updated

Modified white BMW 3 Series E92 with a single turbo through the bonnet, widebody arches and an M3-style bumper

Power by stage

Stock is BMW's US figure. Stages 1 and 2 are tuners' figures at the engine; Stages 3 and 4 are at the wheels (whp), so they read lower than engine power. US 93 octane equals 98 RON, the best fuel sold in Israel.

Stock300 hp
Stage 1360–400 hp Stage 2380–440 hp Stage 3430–480 whp Stage 4600–700 whp

Names with an arrow go straight to that part's product page for this car. Names in a dashed outline are other brands that make the part; exact links for them are being added.

1

Stage 1: Software or a piggyback

360–400 hp

The N54 is known for big gains from software alone. MHD's flash quotes up to 360 hp and 520 Nm at Stage 1 on a stock car (MHD); Dinan's Stage 1 quotes 361 hp and 379 lb-ft (Dinan, at EuroSport Tuning); COBB's Accessport claims up to 30% more power on a 335i at Stage 1 (COBB, at ModBargains); and Burger Motorsports says its JB4 adds up to 100 hp at the crank on a completely stock car (Burger Motorsports).

Typical cost: MHD flasher €109 plus maps €59, Dinan $405, COBB Accessport $675 (ModBargains) or JB4 $479 (BMP Tuning).List prices, Sept 2026, before shipping, import tax and fitting.

Stage 1 tunes compared

TuneTypeClaimed powerPriceNotes
MHD Stage 1Flashup to 360 hp€109 + €59Flasher licence plus map pack
Dinan Stage 1Flash361 hp$405379 lb-ft; loaded by a Dinan dealer
COBB Accessport V3Flash+30% on a 335i$675+21% on a 135i
Burger Motorsports JB4Piggybackup to +100 hp$479At the crank, on a stock car

Parts list

  • Tune required MHD flasherJB4COBB AccessportDinan

    A flash rewrites the engine computer; the JB4 plugs in between the sensors and it.

  • Wastegate rattle fix optional Vargas rattle fixMHD software fix

    MHD's Super licence includes a software fix; Vargas's hardware fix is $94.99 but the turbos must come out.

Before you buyBefore tuning, check the high-pressure fuel pump and injectors: FCP Euro notes the pump's seal degrades over time and BMW issued several recalls (FCP Euro), and BimmerWorld lists index 12 as the known-good injector (BimmerWorld).
2

Stage 2: Downpipes, intercooler and ethanol

380–440 hp

Downpipes free the most power: MHD's Stage 2 maps make up to 380 hp with high-flow downpipes, Stage 2+ with an intercooler up to 420 hp, and its ethanol-blend maps up to 440 hp (MHD). VRSF says its downpipes add 20–25 hp at the wheels (VRSF), and that the stock intercooler gets about 32 degrees hotter during a third-gear pull (VRSF).

Typical cost: VRSF downpipes from $285; VRSF intercooler from $379.99 on sale or Wagner EVO3 $1,150.List prices, Sept 2026, before shipping, import tax and fitting.

Stage 2 results compared

SetupFuelClaimed powerPriceNotes
MHD Stage 295–98 RONup to 380 hp—High-flow downpipes
MHD Stage 2+95–98 RONup to 420 hp—Downpipes and intercooler
MHD E85 blend mapsE25–E60up to 440 hp—Upgraded low-pressure pump for E40 and E60

Parts list

Before you buyCatless downpipes won't pass Israeli inspection, and E85 isn't sold at Israeli filling stations, so the ethanol maps are for countries that have it.
3

Stage 3: Upgraded twin turbos and fuel

430–480 whp

The factory turbos are the next limit. Pure Turbos' Stage 2 twins for the 135i and 335i typically support 430–480 whp on 93 octane (R44 Performance). The extra fuel comes from port injection: Fuel-It's kit for the 135i and 335i adds 550 cc port injectors, a JB4 and a Stage 2 low-pressure pump for up to 650 whp (UroTuning).

Typical cost: Pure Turbos Stage 2 £3,630.53 (R44 Performance); Fuel-It! port injection with JB4 $1,549.95; dual Walbro 450 pump $680.List prices, Sept 2026, before shipping, import tax and fitting.

Turbo upgrades compared

Turbo or kitFuelClaimed powerPriceNotes
Pure Turbos Stage 293 octane (98 RON)430–480 whp£3,630.53Replaces both factory turbos
Fuel-It! port injection + JB4—up to 650 whp$1,549.95550 cc injectors, Stage 2 LPFP
Black Market Parts port injection—≈400–1,000 whp$695.99750 cc injectors; controller extra

Parts list

  • Upgraded twin turbos required Pure Turbos Stage 2VargasRB Turbo

    Bolt-in replacements for the factory turbos.

  • Port injection required Fuel-It! kitBMP kit

    Extra injectors in the intake to back up direct injection.

  • Low-pressure fuel pump required Dual Walbro 450Fuel-It!

    $680 on sale; rated to 1,000 whp on petrol.

Before you buyBudget for the turbos, fuel system, downpipes, intercooler and a custom tune together. Changed turbos aren't road-legal in Israel without approval.
4

Stage 4: Big twins or a single turbo

600–700 whp

At the top, the high-flow version of Pure's Stage 2 twins consistently makes 600–700 whp with the right fuel and tune (BimmerWorld). The other route is a single turbo: DOC Race's top-mount kit takes Precision turbos from 5862 to 6870, and notes the factory injectors generally support about 550 hp (R44 Performance).

Typical cost: Pure Stage 2 HF $3,594.99–$4,169.99 (BimmerWorld) or DOC Race single-turbo kit £4,330.67 (R44 Performance).List prices, Sept 2026, before shipping, import tax and fitting.

Big-turbo builds compared

KitFuelClaimed powerPriceNotes
Pure Turbos Stage 2 HF—600–700 whp$3,594.99–$4,169.99With proper fuelling and tuning
DOC Race top-mount single——£4,330.67Precision 5862 to 6870; left-hand drive
Dual Walbro 450 LPFPPetrol / E85rated to 1,000 / 875 whp$680Fuel supply for the big builds

Parts list

  • Big turbos required Pure Stage 2 HFDOC Race singlePrecisionVargas

    Twins in the stock location, or one big turbo.

  • Fuel system required Port injectionLPFPFuel-It!

    Port injection and a bigger low-pressure pump.

  • Gearbox and clutch required South BendSpecClutch Masters

    Ask the shop what your gearbox will hold at this torque.

Before you buyStage 4 is a full build: choose one shop to fit, tune and stand behind it. The biggest figures need E85, which isn't sold at Israeli filling stations.

Where to buy

OBDeleven's plug-in reader and app offer one-click customisations for Volkswagen-group, BMW, Toyota, Ford and Mercedes-Benz cars. ECS Tuning is a US parts shop that stocks several of the brands in this guide and takes international orders; import tax and duties are charged on delivery. It lists US-market fitments. Check the fit for your car and the shipping cost before you order. We earn a commission on orders through these links, at no extra cost to you (how the site makes money).

Quick answers

How much horsepower does a stock BMW 135i / 335i N54 have?
300 hp from the factory.
How much hp does a Stage 1 BMW 135i / 335i N54 make?
Tuners claim 360–400 hp at Stage 1, up from 300 hp stock (Stage 1 options).
How much hp does a Stage 2 BMW 135i / 335i N54 make?
Tuners claim 380–440 hp with a Stage 2 file and the parts it needs (parts list).
How much hp does a Stage 3 BMW 135i / 335i N54 make?
Tuners claim 430–480 whp at Stage 3: upgraded twin turbos and fuel (Stage 3 parts).
How much hp does a Stage 4 BMW 135i / 335i N54 make?
Stage 4 is the top of the ladder for this car: big twins or a single turbo. The biggest builds claim 600–700 whp. Check which fuel each figure needs: Israel sells 95 and 98 octane only (Stage 4).
How much does a Stage 1 BMW 135i / 335i N54 cost?
List prices: MHD flasher €109 plus maps €59, Dinan $405, COBB Accessport $675 (ModBargains) or JB4 $479 (BMP Tuning).

Watch: real builds

From tuners', shops' and motoring journalists' own YouTube channels. Nothing loads from YouTube until you press play.

1:33
Stage 1UroTuning on the Burger Motorsports JB4 for the N54UroTuning Product Highlights on YouTube
3:43
Stage 2MAPerformance installs 3-inch downpipes on an N54 135i / 335iMAPerformance on YouTube
13:25
Stage 3ACI Dynamix fits Pure Stage 2 turbos to a 335i and measures the gainACI Dynamix on YouTube
11:54
Stage 4Speedhaus: a 1,000+ hp single-turbo 335i with a built engineSpeedhaus on YouTube

All build videos, by car

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Questions to ask the shop

  1. Is my car a 2007–2010 N54, or a later N55?
  2. Has the high-pressure fuel pump been replaced, and are the injectors index 12?
  3. Will you log knock before and after the tune, and is the file written for 98 RON?
  4. Flash or piggyback: which do you recommend for my car, and why?
  5. Do my turbos have wastegate rattle, and how will you fix it?
  6. What torque will my gearbox and clutch take?

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