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.
Engine
B48
Stock
184 bhp · 300 Nm
Stage 3 ceiling
184 bhp
BMW 420i tuning
The BMW 420i (G22 / G23 / G26, 2020–present) runs the B48 2.0L turbocharged inline-four and leaves the factory at 184 bhp · 300 Nm, Rear-wheel drive, 8-speed ZF automatic. Samuel tunes the G22 Coupe, G23 Convertible and G26 Gran Coupe to the same standard — every map hand-calibrated for the specific car, its fuel grade and its installed hardware, not a base file loaded and left. G22 420i Stage 1 alone takes it from 184 bhp · 300 Nm to 280 bhp · 450 Nm on the standard turbo, flashed over OBD on BM3, MHD or MG Flasher.
Add the Stage 2 hardware and the G22 420i targets 320 bhp · 500 Nm; from there the B48 stretches to around 500 bhp on a hybrid or big-turbo build with supporting fuelling. Whichever stage suits the G22 420i, the file is delivered within 24 hours and is fully reversible to the supplied stock calibration.
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
Engine guide
BMW 420i tuning, stages, hardware and what to expect from the G22 B48
The G22 420i runs the entry-spec B48, the same 184 bhp / 300 Nm software calibration as the G20 320i, in the slightly larger 4 Series coupe body. The engine block, head, turbo and fuel system are identical to the 430i's; only the software limiter and a slightly smaller injector spec separate the two. BMW 420i tuning with Samuel exploits that, Stage 1 alone unlocks more torque than a stock 430i makes. BMW 420i G22 Coupe tuning, G23 Convertible tuning and G26 Gran Coupe tuning all use the same map.
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.
Compatibility
Platform and hardware compatibility
Bootmod3 (BM3)
Full B48 support across every chassis in the family (320i, 330i, 420i, 430i, 530i, Z4 sDrive20i). OBD-port flashing on the MEVD17 (early) and MG1CS003 (later) DMEs. Realtime monitoring via the BM3 app, the most widely used platform for B48 tuning.
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MHD
Full B48 support. Suitable for Stage 1 and Stage 2 across the family. Strong data-logging toolset for verifying lambda, ignition correction and intake temperatures after each flash.
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MG Flasher
Full B48 support. Clean interface and reliable flash process on the MG1CS003 DME, a common choice for owners who prefer the MG ecosystem.
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xHP Flashtool
Compatible with the ZF 8HP gearbox fitted to every modern B48 chassis (G20 / G22 / G30 / G29). Available as an add-on, strongly recommended at Stage 2 where torque jumps significantly for a 2.0-litre four. Manual-gearbox cars do not need xHP.
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ECU: MEVD17 / MG1CS003 DME across B48 production. Accessible via the OBD port, no bench flash required for Stage 1 or Stage 2.
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
G22 420i Stage 1 lifts the B48 from a stock 184 bhp · 300 Nm to 280 bhp · 450 Nm, with no hardware required. The map is flashed through the OBD port on BM3, MHD or MG Flasher and is the starting point for almost every G22 420i owner — broader torque and sharper throttle response from the factory hardware.
This page covers the G22 Coupe, G23 Convertible and G26 Gran Coupe (G22 / G23 / G26). They share the B48 2.0L turbocharged inline-four and run the same core calibration, but every G22 420i tune Samuel delivers is tailored to your exact car, fuel grade and installed hardware — never a base map loaded and left.
Stage 2 on the G22 420i targets 320 bhp · 500 Nm and needs downpipe + intake. Everything else — turbo, fuel system, intercooler — holds within the Stage 2 figures on the B48.
On the right hardware spec the B48 in the G22 420i reaches around 500 bhp. Stage 1 and Stage 2 run the standard turbo; beyond that needs a hybrid or full big-turbo conversion with supporting fuelling, and the calibration is built bespoke per car.
Remotely. Once Samuel has your build details, the calibrated G22 420i map is delivered to your flashing tool account (BM3, MHD or MG Flasher) within 24 hours and you flash it yourself over OBD in about 15 minutes. It's fully reversible — the original B48 stock file is supplied before you flash, so the car can return to factory at any time.
A factory warranty can be voided if BMW shows a tune caused a specific failure, so it's a personal call. Samuel's G22 420i maps are calibrated to stay within the mechanical limits of the B48 hardware, and because the tune is reversible to stock before any dealer visit, many owners run a tuned G22 420i without issue.
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