Tuning · BMW M135i (F20 / F21)
M135i
N55
The N55 hot-hatch sleeper in F20/F21 form. Hand-calibrated from Stage 1 through to hybrid and big-turbo builds.
BMW M135i tuning
The MEVD17.2 DME in the F20 / F21 M135i is the same unit shared across the N55 family — same OBD flash path, same hardware ceiling. Samuel starts with the specific car: its fuel grade, installed hardware, and the 322 bhp / 450 Nm factory baseline. Stage 1 revises boost, timing and torque limits to reach 380 bhp / 500 Nm on the stock turbo and standard fuelling, flashed in about 15 minutes via the OBD port. Stage 2 recalibrates around downpipe, intake or panel filter, and intercooler, targeting 420 bhp / 550 Nm; Stage 2+ adds the B58 TU fuel pump and targets 440 bhp / 600 Nm. Stage 3 is bespoke around whatever hybrid or big-turbo spec you submit.
Engine
N55
Stock
322 bhp · 450 Nm
Stage 3 ceiling
322 bhp
Configurator
Build your M135i 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 F20 / F21 M135i (2011–2019) is the 1 Series hot hatch with the N55 single-turbo straight-six — the same engine and MEVD17.2 DME used in the M235i, 335i, 435i and 535i, in the smallest available body. From the factory BMW set it at 322 bhp / 450 Nm in M-Performance trim, rear-wheel drive through the ZF 8HP. Samuel tunes both the F20 5-door and F21 3-door to the same standard — every file calibrated for the specific car, not the platform in general.
Compatibility
This M135i tune runs on Bootmod3, MHD or MG Flasher — all three flash the N55 over OBD. Compare platforms or see full N55 compatibility.
Engine guide
What the M135i map revision covers: N55 stages explained
The MEVD17.2 DME in the M135i controls boost pressure, torque limits and throttle mapping — and the factory calibration leaves headroom in all three parameters. Samuel's Stage 1 map revises each of them for 380 bhp / 500 Nm from the OEM hardware, flashed via OBD. Stage 2 recalibrates around the expanded airflow from downpipe, intake or panel filter, and intercooler, targeting 420 bhp / 550 Nm. Stage 2+ adds the B58 TU fuel-pump conversion and extends the target to 440 bhp / 600 Nm — the fuelling headroom is what lets the N55 hold timing deeper into the operating range. Every file is log-reviewed after the first flash before sign-off.
Stage 1
380 bhp · 500 Nm
No hardware required. The MEVD17 DME is flashed via the OBD port. BMW M135i Stage 1 unlocks 380 bhp and 500 Nm from the OEM hardware (up from 322 / 450 stock). The BMW M135i chip tuning starting point and the most cost-effective change you can make to the F20 / F21 N55 hot hatch.
Every M135i tune Samuel produces is calibrated individually for the specific car, fuel grade and installed hardware, not a base map loaded and left. BMW M135i tuning done correctly accounts for the F20 chassis behaviour, the gearbox calibration and UK fuel quality; the map is reviewed against your data logs after the first flash and revised before sign-off.
M135i specs & stage targets
BMW M135i tuning at a glance
- Engine
- N55
- Body styles
- F20 5-door · F21 3-door
- Chassis codes
- F20 / F21
- Production
- 2011–2019
- Drivetrain
- Rear-wheel drive
- Gearbox
- 8-speed ZF automatic
- Stock output
- 322 bhp · 450 Nm
- Tuning ceiling
- ~800 bhp on the right hardware
| Stage | Target |
|---|---|
| Stage 1 | 380 bhp · 500 Nm |
| Stage 2 | 420 bhp · 550 Nm |
| Stage 2+ | 440 bhp · 600 Nm |
| Stage 3, Hybrid Turbo | Up to 800 bhp depending on spec |
| Stage 3, Big Turbo Kit | Up to 800 bhp depending on spec |
FAQ
M135i tuning — frequently asked questions
The calibrated M135i map is delivered to your BM3, MHD or MG Flasher account within 24 hours of payment confirmation. You flash it over OBD yourself in around 15 minutes — Samuel personally calibrates every file, no automated delivery.
Yes — the original N55 stock file is supplied before you flash, so the car can return to factory calibration at any time. The flash process takes the same 15 minutes in reverse.
A factory warranty can be voided if BMW attributes a specific failure to the tune — that's a personal call. Samuel's M135i maps are calibrated to stay within the mechanical limits of the N55 hardware, and the tune is fully reversible to stock before any dealer visit. Many owners run a tuned M135i without issue.
BM3 is the most widely used for the N55 family and the best pick if you want realtime monitoring through the app. MHD covers Stage 1 through Stage 2+ cleanly and has a strong data-logging toolset. MG Flasher is a clean alternative for owners already in that ecosystem. The calibration Samuel delivers is the same on all three.
Yes. Once you've driven the M135i on the new map, send your data logs back through your platform (BM3, MHD or MG Flasher) and Samuel reviews them before sign-off. If anything needs adjusting, the file is revised. That review step is what separates this from a generic off-the-shelf map.
Keep exploring
Keep exploring M135i tuning
Other N55 models we tune: M2 (N55), M235i, 135i, 335i, 335i (E90), 435i.
Engine guide
N55 tuning
Every N55 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 M135i, 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