BMW M135i F20: Stage 1 + xHP Stage 3

Another properly set up BMW M135i F20 dialled in with our full engine and gearbox package. This N55-powered hot hatch came in for a custom Stage 1 dyno calibration paired with xHP Stage 3 gearbox software, all developed live on our 4WD linked V-Tech dyno.

The numbers

It arrived producing 321bhp and 484Nm on our baseline run. After the Stage 1 calibration and xHP Stage 3, it left making 401bhp and 682Nm, measured on the rollers, not estimated:

What the transformation feels like

That’s +80bhp and +198Nm, and the focus here was controlled, usable power. The N55 turbo platform responds exceptionally well when calibrated correctly, instant throttle response, a huge surge through the mid-range and relentless pull through the gears, all while keeping delivery smooth and consistent.

Why xHP Stage 3 matters

With xHP Stage 3 installed, the ZF8 automatic is completely sharpened up. Shift speeds are faster, torque management is optimised and the gearbox logic under load becomes far more decisive, letting the car fully utilise the increased output safely and effectively, rather than the factory software holding it back.

How it was done

All work was carried out live on our V-Tech 4WD linked dyno, with a full health check before any tuning and detailed data logging throughout. The calibration was written for this exact car, its ECU variant, its fuel, its condition. No generic files. No shortcuts. Just precision N55 tuning done properly, with the original software backed up so it’s fully reversible.

Your M135i could be next

M135i, M140i or another turbo BMW, we can transform how it drives. See our full BMW M135i tuning page, our engine + gearbox tuning page for packages, check your car’s gains, or get a free quote and we’ll book you in.