B58 Gen 2 · 3.0 single-turbo inline-six
The B58 Gen 2 runs on Bootmod3 and MHD. Both platforms are fully supported, both flash the ECU remotely, and both put your custom map on the car through an app on your phone. No rolling road, no workshop visit, no car leaving your drive. The Gen 2 uses a later DME generation than the original B58, so the unlock procedure is different. Not every VIN ships locked from the factory. Samuel confirms from your VIN before the build starts and tells you exactly what your car needs before you commit to anything.
B58 Gen 2 vehicles
SamuelTuned covers B58 Gen 2 tuning and remapping across the BMW M240i (G42), BMW M340i (G20 / G21), BMW M440i (G22 / G23 / G26), BMW Z4 M40i (G29), BMW X3 M40i (G01 / G45), BMW X4 M40i (G02) and Toyota Supra 3.0 (J29 / DB). Each one gets a custom, individually-calibrated remote ECU remap — Stage 1, Stage 2 and Stage 3. Open the configurator on your car to choose your stage, add the options that fit, and send the full build to Samuel.
G42
M240i
374 bhp stock
M240i Configure Tuning
G20 / G21
M340i
374 bhp stock
M340i Configure Tuning
G22 / G23 / G26
M440i
374 bhp stock
M440i Configure Tuning
G29
Z4 M40i
382 bhp stock
Z4 M40i Configure Tuning
G01 / G45
X3 M40i
374 bhp stock
X3 M40i Configure Tuning
G02
X4 M40i
374 bhp stock
X4 M40i Configure Tuning
J29 / DB
Supra 3.0
382 bhp stock
Supra 3.0 Configure Tuning
Engine guide
Bootmod3 is the primary platform for B58 Gen 2 builds at SamuelTuned. Your custom map is delivered over-the-air to the BM3 app and you flash it yourself at home. In-app logging means Samuel can pull your datalogs remotely and refine the calibration without the car moving. For E85 and flex-fuel builds, BM3 handles ethanol switching natively and is the stronger choice for high-output Gen 2 setups where you want the map updated as the build evolves.
MHD is fully supported on the B58 Gen 2 and works through the same app-based process: map delivered to the app, flashed at home, logs sent back for refinement. If you are coming from a previous MHD car or prefer the interface, it is a capable platform for Stage 1, Stage 2 and E85 builds on the Gen 2. Samuel tunes on both and will point you to the right one based on your goals and setup.
The Gen 2 B58 uses a newer DME than the original B58, and the unlock process is not the same. Some Gen 2 cars ship locked from BMW, some do not. Samuel checks your VIN before the build starts. If your car needs an unlock, it is included in the quote with no surprises.
The B58 has one of the strongest stock bottom ends BMW makes. The Gen 2 brought a more modern DME and better thermal management, which gives the engine more room to work with on a custom map. The stock turbo responds well at every stage. Stage 1 is the best return on this engine: a big power step with no hardware at all. Stage 2 adds a downpipe and intake, which opens up more top-end and lets the turbo sustain boost properly. E85 is where the largest gains come from on pump-friendly hardware, and a hybrid or upgraded turbo raises the ceiling further for bigger builds. A custom map makes a real difference here because a generic file has to cover every car in every market. Samuel maps to your datalogs, your fuel and your specific setup. On Supra builds, gearbox calibration on xHP runs alongside the engine map so shift behaviour and torque limits are matched to the rest of the tune.
Tune stages
Stage 1
~440–470 bhp
Software only on the stock turbo. A big step over standard with no hardware required.
Stage 2
~480–510 bhp
Downpipe + intake. More top-end pull and sustained boost over Stage 1.
E85 flex
520+ bhp
Flex-fuel kit + dedicated ethanol map. The biggest safe gains on stock-turbo hardware.
Hybrid turbo
Quoted per build
Upgraded turbo + supporting fuel and hardware. Bespoke calibration around your setup.
Figures are indicative and depend on the exact model, fuel and supporting hardware. Every tune is calibrated individually — open the configurator for your car for the precise build and price.
FAQ
Bootmod3 and MHD both fully support the B58 Gen 2. Both are flashed remotely: your map is delivered to the app and you flash it at home. Samuel will recommend the right platform for your goals and setup.
It depends on your VIN. Some B58 Gen 2 cars are locked from the factory, some are not. Samuel confirms from your VIN before the build starts and includes the unlock in the quote if your car needs one.
You flash the map yourself using the Bootmod3 or MHD app on your phone. Samuel sends the custom map file after calibrating it to your datalogs. No rolling road, no dealer visit, no car moving. The platform guides on site walk through the full process from scratch if it is your first time.
No. Stage 1 is software only on stock hardware. No downpipe, no intake, no parts to source or fit. Hardware comes in at Stage 2.
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Platform
Our primary flash platform for B58 Gen 2 builds: app-driven, OTA custom map delivery.
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