BMW M340i G20Stage 1 to Stage 4 tuning guide

On 95 or 98 octane, Stage 1 files claim 400–460 PS, but most need the engine computer unlocked first.

Typical cost: bootmod3 $595 plus a bench unlock ($215 mail-in, or $850–$1,500 FEMTO on 06/2020+ cars); BR-Performance €890; G-Power €1,995 fitted; plug-in boxes $599 (JB4) or €609 (RaceChip); xHP gearbox software from $299.99.List prices, Sept 2026, before shipping, import tax and fitting.

Unlocking the engine computer first

bootmod3 says cars with BMW software from November 2019 need a bench unlock before OBD flashing (its page). Computers built before June 2020 can be mailed in for unlocking ($215 at DUDMD); those built from June 2020, which includes every facelifted car, can only be unlocked by FEMTO, at $850–$1,500 (a dealer page). After that, bootmod3, MHD and EcuTek flash by OBD. Plug-in boxes (JB4, dAHLer, RaceChip) need no unlock.

Stage 1 tunes compared

Cobb has no G20 support. For the gearbox, xHP sells 8-speed software from $299.99 that raises the factory torque limits (its page).

With a downpipe and intake, bootmod3's Stage 2 claims +22% power on 95 octane and +25% on 98 (its page), and 117 Speed claims 480 bhp (its guide). European cars can keep their particulate filter: HJS and Aulitzky sell ECE-approved downpipes that do.

Typical cost: downpipe $479.99 (VRSF) to $1,424.99 (Active Autowerke); heat exchanger $699 (CSF) or $749.99 (Mishimoto); Eventuri intake $1,495; AWE exhaust from $1,755.List prices, Sept 2026, before shipping, import tax and fitting.

• Downpipe required HJS ECE downpipeAulitzky ECE downpipeVRSF / Active Autowerke (ECS Tuning)

  HJS's 300-cell and Aulitzky's 200-cell downpipes are ECE-approved and keep the filter. VRSF's catted pipe is $479.99 and Active Autowerke's $1,424.99 at ECS Tuning, without road approval.

• Intake and cooling recommended Eventuri carbon intakeCSF / Mishimoto / BMS (ECS Tuning)Wagner intake manifold (ECS Tuning)

  Eventuri's intake costs $1,495. The B58 cools its air with water, so the upgrade is a bigger heat exchanger: CSF's is $699 and Mishimoto's $749.99, and charge pipes from BMS and Mishimoto cost about $300–$350. Wagner's manifold with a bigger built-in intercooler costs $2,490.

• Exhaust optional Akrapovič titaniumRemus (ECE)EisenmannAWE

  Akrapovič's titanium slip-on is about €6,609 and needs a BMW valve; Remus's axle-back has ECE approval; Eisenmann's is about €2,891; AWE's Track Edition starts at $1,755.

G-Power's GP-510 uses an uprated turbo for 510 PS and 690 Nm. Pure Turbos' Gen 2 PURE600 is rated at 550+ whp with supporting parts, from $1,095 at ECS Tuning (ECS Tuning). More fuel comes from Dorch's high-pressure pump (about $2,199, rated 770 whp on petrol, a dealer page) and Precision Raceworks' 750 cc port injection (about $799–$899, Turner).

• Upgrade turbo required Pure Turbos (ECS Tuning)VargasTurbo (ECS Tuning)G-Power GP-510

  VargasTurbo's B58TU turbo is rated up to 650 whp. Each needs its own tune, plus the Stage 2 parts.

• Fuel system required Dorch DS25 pumpPrecision Raceworks port injection

  Port injection is sold mainly for ethanol blends, which Israel doesn't sell; on 98 octane the pump is the main upgrade.

Pure's PURE800 and PURE900 are rated at 700+ and 800+ whp ($3,107 and $3,626, Pure's page), but figures like these are made on ethanol or race fuel. On 98 octane, expect much less. Builds at this level add the fuel pump, port injection and gearbox software from Stage 3; we didn't find maker-listed forged internals for this engine.

• Big turbo required Pure 800 / 900Dorch pumpPort injectionxHP gearbox software

  Plan the fuel system and gearbox together with the turbo.

• Springs and coilovers maker lists it H&R sport springsDinan springsAC Schnitzer springsKW V2KW V3

  H&R's springs lower the xDrive car about 30 mm and work with the adaptive dampers. KW's V3 costs $3,044 for cars without electronic dampers and $3,784 with them.

• Brakes maker lists it BMW M Performance brake kit

  BMW's own kit has four-piston Brembo front calipers and needs at least 18-inch wheels.

• Body kit maker lists it BMW M Performance carbon splitterMaxton splittersADRO carbon winglets (facelift)

  BMW's M Performance carbon parts are factory parts; Maxton and ADRO sell aftermarket ones.