ECU Remap BMW M340i (G20) & M440i (G22) – B58 3.0L

ECU Remap BMW M340i (G20) & M440i (G22) – B58 3.0L

*Please note with late 2020 models the ECU may be locked, if it is, we offer an ECU unlocking service for £1500 with the required flasher*

Let’s be honest, the G20 M340i and G22 M440i are already devastatingly quick in the real world. That B58 3.0-litre turbo straight-six is smooth, tough and responds brilliantly to a smart calibration. But from the factory, there’s headroom left on the table—softened throttle mapping, torque limits in lower gears and a power curve that fades earlier than it needs to.

At MSL Performance in Birmingham, we unlock what BMW kept in reserve. No off-the-shelf files—every car is custom-calibrated on our dyno for your fuel, your hardware and how you actually drive. Think of it as a bespoke suit for your B58: sharper, stronger and totally safe.

Find Your Perfect Level of Power

Every driver is different. Choose the stage that suits how you use the car—from OEM+ refinement to a more serious, hardware-supported setup.

Stage 1: The “This Is How It Should’ve Been!” Tune

On completely standard hardware, we optimise boost control, torque targets and throttle mapping while retaining factory safety strategies. The result is a car that feels lighter on its feet and pulls harder everywhere.

How it feels:

• Crisper throttle and reduced lag

• Stronger mid-range shove for effortless overtakes

• Clean, sustained pull to the top end

The Result:

• Around +45 bhp

• Around +40 lb-ft of additional torque

What you need:

• Just your car (stock hardware is fine)

• 97/99 RON fuel recommended for best results

• Optional: performance panel filter

Stage 2: For When You Want to Make a Statement

Free up the exhaust and improve charge-air control, and the B58 really wakes up. With supporting hardware, we can run a more assertive calibration safely and repeatably.

How it feels:

• Noticeably harder mid-range and stronger top-end

• More urgent in-gear acceleration from 3rd upward

• Consistent performance, even on back-to-back pulls

The Result:

• Up to around +65 bhp over stock (hardware, fuel and conditions dependent)

• A substantial torque increase across the rev range

What you need:

• High-flow downpipe (sports cat or decat—observe local regulations/OPF considerations)

• Upgraded intercooler strongly recommended

• Intake/panel filter preferred

• Optional: uprated spark plugs; ZF8 TCU/gearbox calibration for sharper shifts and better torque delivery

So, Why Come to MSL?

• Custom dyno mapping — no generic files

• Reliability-first approach — we chase usable, repeatable gains, not pub-talk peaks

• Honest advice — sensible hardware planning that fits your goals

• Full package support — from filters and intercoolers to downpipes and gearbox tunes

Ready to feel the car BMW should’ve built?
Give us a call or drop into our Birmingham workshop. We’ll talk you through Stage 1 vs Stage 2, the right hardware, and build a plan to unlock your M340i or M440i’s true potential.