G23 Tuning
BMW's 430i Convertible, M440i Convertible, 2021–2026. Powered by the B48/B58 engine family.
Stage pricing for the G23
Cooling, downpipe, fueling — the ceiling worth chasing on factory turbos.
Build this stage Stage 2 methodologyBigger fueling, often a hybrid or Phantom turbo. Per-car.
Build this stage Stage 3 methodologyThe G23 is the 4 Series Convertible — the G22 coupe with a folding soft-top, traded for open-air motoring. Same platform, same engines: the M440i runs the B58 (382 hp), the 430i the B48 four (255 hp), and both tune exactly as they do in the coupe (full story on the G22 and G20 pages, including the current-gen locked-ECU/piggyback route the G42 page explains).
What the convertible adds is weight and open sky; what it gives up is a little of the coupe's rigidity. That makes the G23 the 4 Series for people who value the drive's feel over its last tenth — a B58 cruiser you tune for effortless real-world pace, not lap times.
So the open-top 4 is the coupe's mechanicals in the body for sunshine: same six, same build path, more reasons to take the long way home.
Parts that fit the G23
DR Forged wheels for the G23
Custom, made-to-order forged wheels — built to your car's spec, so any of them fits the G23. Pick the look; we build the fitment.
Tech essays for the G23
Tuning and Your Warranty: What's Reversible, and What's Actually Detectable
The honest version of the warranty question — what Magnuson-Moss actually says, what we flash back before a dealer visit, and what...
ReadUpgraded Stock-Frame Turbos: Response vs. Max Power — Why We Build Two
Why we build two upgraded stock-frame turbos: Stage 1 for response and driveability, Stage 2 for maximum power from the stock frame...
ReadB48 Tuning Guide: Stages, Supporting Mods, and What Actually Holds Up
The definitive B48 platform reference for BMW and MINI owners: what each stage changes, which supporting mods Stage 2 needs, when the...
ReadFEMTO & the Bosch DME Lock Guide for BMW & MINI
When it comes to tuning modern BMW and MINI vehicles, enthusiasts have encountered significant challenges starting with the 2020+ models. Bosch's updated…
ReadUpcoming events
Cars & Coffee Delray Beach
Cars & Coffee Miami — Jungle Island Father's Day
Supercar Sundays Florida — Father's Day Car Show
Set the G23 as your garage vehicle and the rest of the store filters to what fits it.
Set vehicleBefore you tune.
Will my dealer flag the tune at service?
The bootmod3 flash is non-destructive and reversible. Revert to stock before a dealer appointment and the ECU is back to factory in a few minutes; re-flash after service. We document the revert step in writing so the next person opening your file knows what's there.
Is it safe for the engine?
Every tune we ship has been datalogged on the car it was written for. We look at knock counts, fuel trims, boost behavior, and intake temps before we sign off. If the numbers don't sit right, we revise. That review and the revision policy are built into what the tune costs.
How long until I have a working tune?
Most calibrations turn around in a few days. We log, review, and revise before anything ships — we would rather get it right than get it out fast.
Can I go back to stock?
Yes. bootmod3 supports a stock revert that returns the ECU to factory calibration in under five minutes. The flash is non-destructive — nothing in the BMW DME is permanently modified. Most owners revert before trade-in.