Built by tuners, for tuners

Custom BMW gearbox tuning,
taken to the next level

Transbrake, bump, traction control, anti-lag — flashed and logged from the 303 app.

Get Started See the tool
Windows
Android
iOS
The Tool

One app, full control

One app to flash, datalog and dial in your gearbox — Windows, Android and iOS. Buy a package and your license activates instantly, so you (or your tuner) can adjust the car whenever you want — no shop visit, no waiting. You even get a push notification on your phone the moment a new tune is ready.

303 app — vehicle & flash menu
Flash

Flash your tune yourself

Write regular and custom-code gearbox files straight from the app over your BMW cable — no shop visit, no proprietary hardware lock-in.

303 app — live gearbox datalog
Datalog

Log engine & gearbox

Full datalogging for both ECUs. With our custom code, the gearbox logs at high speed — the resolution you need to actually see what the transmission is doing.

303 app — transmission adaptations
Adaptations

Read & clear adaptations

Read and reset the transmission's adaptation values right from the app — clean baseline after a flash, hardware change or clutch service.

303 app — flash options incl. 303 custom
Flash Options

Flash options — normal & custom

A full set of options for regular tunes, plus exclusive options on files that carry our custom code. Editable by you or by your official 303 tuner through the portal.

Custom Code

What custom code unlocks

Custom code is our own firmware for the ZF 8HP, developed by reverse-engineering the transmission. It turns on features and flash options the stock software was never built to do.

  • Transbrake in 1st and 2nd gear
  • Bump control — two selectable modes
  • Custom stall function
  • Closed-loop clutch-slip control
  • Custom converter (WK) control after launch
  • Upshift patch — fixes upshift RPM issues
  • Lock 1st or 2nd gear on the fly
  • Map switching on the fly
  • Transbrake on the foot brake
  • Traction control built into the gearbox
  • Anti-lag from the gearbox
  • High-speed gearbox datalogging
  • Anti-theft map slot
  • Burnout mode with AWD disable on the fly
We teach you how to use it

After you register in the user portal, you get access to our training program — step-by-step videos that walk you through every function — plus one-on-one video-call assistance after your purchase. You're never left figuring it out alone.

Packages

Choose your package

Every package is a gearbox tune plus the app license to flash and live with it. Pick one and tell us about your build — we handle the rest.

Gearbox Custom Tune

Fully custom gearbox calibration, dialed to your exact build.
Starting at$750USD · app license included
  • Fully custom calibration
  • Flash from Windows / Android / iOS
  • Engine & gearbox datalog
  • Adaptations read & clear
  • Standard flash options
Get Started
Most complete

Gearbox Custom Tune + Custom Code

Our custom code — transbrake, bump, anti-lag, traction control, and the full custom feature set.
Starting at$1,500USD · app license included
  • Everything in Custom Tune
  • Custom code features unlocked
  • Exclusive custom flash options
  • High-speed gearbox logging
Get Started

Every package includes the app license. Starting prices — optional features can increase the total. Flash, datalog and adjust from Windows, Android or iOS.

Partners

Our partner tuners

Our trusted partners — shops and DME tuners that work with us. They handle the engine; we handle the gearbox.

SamTuned
Darwin Performance
Visconti Tuning
Dark Horse
MikeyTuned
Osprey
ReproPower
Perfortech Motor Sports
The Shop CT
Serks Motorworks
Avus Motorsports
Uthu Noa Performance
Want to become a partner? Run a shop or tune BMW DMEs? Join the 303 network.
Become a partner
More

We also do engine

Gearbox is our focus — but the same 303 app does a lot more. Custom tunes and custom code for the BMW MG1 DME, engine flashing, gearbox ISN & swaps, FSC feature codes and high-speed RAM logging.

Engine · DME

DME Custom Tune

Fully custom engine calibration for the BMW MG1 DME — power, torque and drivability dialed to your exact build.

BMW DME · MG1
Engine · DME

DME Custom Code

Firmware features for the MG1 DME — map switching, flex fuel, launch control, anti-lag and pops / flames.

BMW DME · MG1
Flash engine mapsWrite and read MG1 DME files from the same app — no extra tool.
Gearbox ISN & swapsRead and reset the gearbox ISN and handle full gearbox swaps.
Enable FSCsTurn on BMW feature codes (FSC) — factory functions unlocked.
RAM loggingHigh-speed RAM datalogging for both engine and gearbox.
Want engine work too? Ask us what we can do for your DME. Talk to us
Get in touch

Talk to us

Questions about a build, a package, or becoming an official tuner — reach out and we'll get back to you.

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