Tuning · BMW 420i (G22 / G23 / G26)
G22 420i
B48
The entry-point B48 in coupe and Gran Coupe form. Hand-calibrated from Stage 1 to a hybrid-turbo build. Choose your package, send your build to Samuel, and get a tune that fits the way you actually drive.
BMW 420i tuning
BM3, MHD and MG Flasher all support the 420i's MEVD17 / MG1CS003 DME through Stage 1, Stage 2 and Stage 3 — whichever tool you're on, the calibration Samuel delivers is the same. The G22, G23 and G26 leave the factory at 184 bhp · 300 Nm; Stage 1 takes that to 280 bhp · 450 Nm with no hardware required. Stage 2 targets 320 bhp · 500 Nm with downpipe + intake, and the B48 has the headroom to go considerably further on a hybrid or big-turbo build.
Engine
B48
Stock
184 bhp · 300 Nm
Stage 3 ceiling
184 bhp
Configurator
Build your G22 420i tune
Choose your stage — Stage 1, Stage 2 or Stage 3 — add the options that fit your car, and send the full build to Samuel for a custom remote remap. He'll quote, schedule, and personally calibrate within 24 hours of confirmation.
Add a stage or add-on
£0
About this tune
The G22 420i page covers the Coupe, Convertible and Gran Coupe — same B48, same DME, same stage targets across all three body styles. Every map Samuel delivers is built for your specific car, your fuel grade and whatever hardware it's running, not pulled from a base file.
Compatibility
This G22 420i tune runs on Bootmod3, MHD or MG Flasher — all three flash the B48 over OBD. Compare platforms or see full B48 compatibility.
Engine guide
B48 in the G22 420i: why it responds to tuning
BMW set the 420i at 184 bhp · 300 Nm from the factory; the B48 block, head and turbo underneath are shared with the 430i — only the software calibration and injector spec separate the two badges. Stage 1 closes most of that gap: 280 bhp · 450 Nm from the stock hardware, no parts required, and Stage 1 alone already exceeds the 430i's stock torque figure. Stage 2 pushes further once downpipe + intake are in place, targeting 320 bhp · 500 Nm; beyond that the B48 scales well on a hybrid or big-turbo build up to around 500 bhp on the right spec.
Stage 1
280 bhp · 450 Nm
No hardware required. The MG1CS003 / MEVD17 DME is flashed via the OBD port, boost pressure, ignition timing, fuel delivery and torque limiters all revised. BMW 420i Stage 1 unlocks 280 bhp / 450 Nm from the OEM hardware (up from 184 / 300 stock). One of the largest single-software gains available on any modern BMW because the factory 420i limiter is so conservative.
Every 420i tune Samuel produces is calibrated individually for the specific car, fuel grade and installed hardware, not a base map loaded and left. BMW 420i tuning done correctly accounts for the G22 chassis behaviour, the 8HP gearbox calibration and UK fuel quality; the map is reviewed against your data logs after the first flash and revised before sign-off.
G22 420i specs & stage targets
BMW 420i tuning at a glance
- Engine
- B48 · 2.0L turbocharged inline-four
- Body styles
- G22 Coupe · G23 Convertible · G26 Gran Coupe
- Chassis codes
- G22 / G23 / G26
- Production
- 2020–present
- Drivetrain
- Rear-wheel drive
- Gearbox
- 8-speed ZF automatic
- Stock output
- 184 bhp · 300 Nm
- Tuning ceiling
- ~500 bhp on the right hardware
| Stage | Target |
|---|---|
| Stage 1 | 280 bhp · 450 Nm |
| Stage 2 | 320 bhp · 500 Nm |
| Stage 3, Hybrid Turbo | Up to 500 bhp depending on spec |
| Stage 3, Big Turbo Kit | Up to 500 bhp depending on spec |
FAQ
G22 420i tuning — frequently asked questions
The B48 in the 420i leaves the factory at 184 bhp · 300 Nm. Stage 1 moves that to 280 bhp · 450 Nm — no hardware required. The map goes in via OBD on BM3, MHD or MG Flasher; broader torque, sharper throttle, all from the OEM hardware.
This page covers the G22 Coupe, G23 Convertible and G26 Gran Coupe (2020–present). All three share the B48 2.0L turbocharged inline-four and run the same core calibration — but every map Samuel delivers is built to your car's specific fuel grade and hardware, not a base file loaded and left.
Stage 2 on the G22 420i targets 320 bhp · 500 Nm and requires downpipe + intake. Turbo, fuel system and intercooler all hold within Stage 2 on the standard B48 hardware spec.
Stage 1 and Stage 2 both run the standard turbo. Beyond that — hybrid turbo or a full big-turbo conversion with supporting fuelling — the ceiling lands around 500 bhp. The calibration at that point is built bespoke around the specific hardware and fuel setup you submit; there is no fixed Stage 3 price because there is no fixed Stage 3 spec.
The 420i runs a ZF 8HP automatic, and xHP responds well to the torque increase at Stage 2 and above — firmer shifts, higher torque limits, and launch control dialled to the build spec. At Stage 1 it is optional but noticeable. Available as an add-on in the configurator above. Manual-gearbox cars do not need xHP.
Keep exploring
Keep exploring G22 420i tuning
Other B48 models we tune: G20 320i, 330i, 330e, 430i, 530e, 530i.
Engine guide
B48 tuning
Every B48 BMW we calibrate, with the full Stage 1, 2 and 3 breakdown for the engine.
Learn moreStages
Stage 1 & Stage 2 explained
What separates Stage 1 from Stage 2 on the G22 420i, the real-world gains and the hardware each one needs.
Learn morePricing
How tuning is priced
How the licence, off-the-shelf maps and custom calibration are priced. We quote your exact spec, never a fixed menu.
Learn moreGuide
What is bootmod3?
New to remote flashing? A plain-English explainer on the platform and how a custom map reaches your car.
Learn more