The BMW M340i is a performance-focused powerhouse straight from the factory, but enthusiasts know there’s way more under the hood waiting to be freed. Upgrading to a Stage 2 tuning kit transforms the driving experience—unlocking significantly more horsepower, torque, sharper throttle response, and a growl that’ll make heads turn. In this 1,400‑word guide, we’ll explore what makes Stage 2 tuning special, break down essential hardware and software components, compare top providers, and offer real-world tuning insights and best practices.
🧠 What Defines “Stage 2” for the M340i?
Stage 2 tuning isn’t just a software flash—it’s a coordinated package of bolt-on upgrades designed to improve airflow, exhaust flow, and engine management. On the B58-equipped M340i, key Stage 2 elements include:
- Downpipe or decat downpipe – frees turbo back-pressure
- Upgraded intake or high-flow air filter – improves airflow into the engine
- ECU flash tuned for octane, downpipe, intake, possibly flex-fuel
- Optional Transmission tune – sharpens shifts and torque handling in the ZF 8-speed
- Cooling and ignition upgrades – sometimes needed for sustained high-load use
Result? You’re looking at 450–500+ hp and 600–700 Nm of torque—dramatic gains over the 380 hp stock rating :contentReference[oaicite:0]{index=0}.
Performance Uplift at a Glance
| Stage | Hardware | Estimated Power (hp) | Estimated Torque (Nm) | Typical Components |
|---|---|---|---|---|
| Stage 1 | Software only | 420–440 | 550–600 | ECU flash, sometimes intake |
| Stage 2 | Intake + DP + software | 450–500+ | 600–700+ | High-flow downpipe, intake, flex-fuel, ECU & TCU tune |
| Stage 3 | Hybrid turbo, full supporting mods | 550–600+ | 700–800+ | Turbo upgrade, LPFP, injectors, fuel pumps |
Real Owners Speak: M340i Stage 2 Results
“Recently got my 2020 M340i back from the tuner… catted downpipe, intake, Visconti flex fuel (running e50), and Ecutek.”
— r/BMW owner with over 500 hp Stage 2 build :contentReference[oaicite:1]{index=1}
Even with huge gains, some owners note that traction, tires, and transmission software heavily influence 0‑60 times—but the midrange surge and passing power are unmistakable.
Top Stage 2 Kits for BMW M340i
1. Active Autowerke Stage 2 Software Bundle
- Content: ECU flash, can include high-flow cat/downpipe stage
- Power gains: +80 hp, +100 Nm—testing above shows ~480/480 at wheels :contentReference[oaicite:2]{index=2}
- Features: Off-road DP maps, cold-start deletes, burble maps, TCU upgrades
2. Dinan Stage 2 Performance Package
- Dinan is known for warrantied tuning through official dealers :contentReference[oaicite:3]{index=3}
- Includes ECU flash, TCU changes, optional intake/downpipe/suspension—engineered for reliability
- Stage 2 gets you similar mid-450s hp with refined drivability
3. Onyx Performance Stage 2 + Hardware Support
- Bespoke UK-based tuning specialists for G20 M340i :contentReference[oaicite:4]{index=4}
- Stage 2 gains ~480 hp and 700 Nm with essential mods, plus recommended coil and plug upgrades
- Dyno-backed, rolling road verified tuning
4. DME Tuning Stage 2 Flash
- ECU-only flash priced ~$3,200 with hardware assumed :contentReference[oaicite:5]{index=5}
- Delivers 480 hp/480 Tq across RPM, includes top-speed removal, burble, cold-start control
Stage 2 Tuners Compared
| Tuner | Hardware | Software | Power Gain | Extras | Price Range |
|---|---|---|---|---|---|
| Active Autowerke | DP, intake optional | ECU flash—with maps for octane, DP | +100 hp / +90 Nm | Burble, cold-start, transuion | $700 software; $1,500+ complete |
| Dinan | Intake, DP, suspension optional | Streetable ECU + TCU | +70–80 hp | Warranty, drivetrain tuned | $2,500–4,500 |
| Onyx Performance | DP, intake, plugs & coils | Custom ECU + TCU | ~480 hp / 700 Nm | Dyno, shift tune, reliability parts | Contact for quote |
| DME Tuning | DP, intake required | ECU-only | 480 hp / 480 Tq | Burble, cold-start | $3,199 |
Hardware Checklist for Stage 2 Reliability
- Decat or high-flow downpipe (catted for emissions compliance)
- Cold-air intake or high-flow panel filter
- Transmission tune (e.g., xHP, Dinan TCU) to handle torque and ensure shift timing
- Upgraded spark plugs & coils especially for sustained WOT on E50/flex-fuel
- Cooling enhancements: Larger chargepipes, intercoolers, high-temp fluids
- Exhaust upgrades if you want sound as well as flow
Stage 2 Installation Workflow
- Install hardware: intake + downpipe + plugs/coils.
- Flash ECU (send in or OBD as allowed).
- Add TCU flash while in boot.
- Dyno and road-test—verify AFRs, knock, coolant, heat.
- Adjust driveshaft/TCU settings for smooth launch.
- Check emissions/CEL: street DP maps vs off-road DP maps.
BMW Owner Advice & Traction Notes
Stage 2 M340i cars can spin tires aggressively—tire pressure, compound, and launch strategy matter:
- “0‑60 didn’t improve much… I spin tires off the line when traction control is off.” r/BMW owner advises upgrading tires and using xHP launch tune for gains :contentReference[oaicite:6]{index=6}.
- Tire upgrades (Michelin PS4, etc.) or switching to summer rubber dramatically improve launches.
Track vs Daily Use Considerations
- Daily driver: Street DP, flex-fuel for pump octane, TCU flash, moderate driving maps
- Track setup: Performance DP, aggressive TCU, high-octane or E85, upgraded cooling
- Winter use: Swap in stock DP map for emissions compliance as needed
Maintenance & Service Lifecycle
- Change oil with high-temp synthetic every 5k–7k miles
- Inspect DP & downpipe for cracks after heat cycles
- Monitor spark plugs every 20k miles depending on fuel type
- Retune after major software updates (iDrive resets can relock ECU)
How to Choose the Right Stage 2 Package
| Goal | Recommended Kit | Why |
|---|---|---|
| Absolute streetable performance & warranty | Dinan Stage 2 | Integrated hardware/software with dealer backing |
| Maximum power and torque with tuning flexibility | Active Autowerke or Onyx | Custom hardware + aggressive maps |
| Simple software upgrade | DME Tuning | ECU flash only; must add hardware separately |
| Balanced EU-based solution | Onyx Performance | UK/D-model specifics, full map + hardware |
Conclusion
Stepping into Stage 2 territory takes the already potent M340i and transforms it into a seriously fast, responsive, and engaging machine. Whether you opt for the all-in-one reassurance of Dinan, the pure performance thrust from Active Autowerke, or the custom UK attention of Onyx Performance, each package delivers real gains. Pairing that with proper tires, TCU tuning, cooling upgrades, and routine maintenance ensures not just excitement—but longevity.
Share your M340i model year, goals, or questions below—I’d love to help you pick the perfect Stage 2 setup for your needs!