Introduction

The BMW M2 Competition is widely regarded as one of the most engaging driver’s cars of its era, blending a compact, rear-drive chassis with the potent S55 engine. Its stock output of 405 hp and 406 lb-ft of torque already delivers exhilarating performance, but for owners who crave more, the APR Stage 3 Turbo Upgrade Kit offers a direct path to 550+ wheel horsepower. Priced at roughly $3,800 for the core hardware, this kit transforms the M2 Competition into a serious track-day weapon and street sleeper. This article provides a detailed breakdown of what the APR Stage 3 kit includes, the installation process, real-world performance gains, total cost considerations, and how it compares to other big-turbo options.

The APR Stage 3 Kit: What’s Included?

APR has long been a benchmark in VAG (Volkswagen Audi Group) performance tuning, and their Stage 3 kit for the S55 engine is no exception. Unlike simpler bolt-on upgrades, Stage 3 involves replacing the factory turbocharger with a larger unit and reworking the induction, intercooling, and fuel systems to support the added airflow. The kit is engineered for a direct fit on the M2 Competition, meaning no custom fabrication is required.

Turbocharger Upgrade

The centerpiece of the kit is a larger, ball-bearing turbocharger. APR’s unit features a billet compressor wheel and an upgraded turbine housing that flows significantly more air than the stock M2 Competition turbo. This increase in airflow is the primary driver of the 550+ hp gains. The ball-bearing core reduces spool lag compared to traditional journal bearings, helping the engine build boost quickly even with the larger compressor. APR rates the turbo to support up to 600 hp at the crank with supporting mods, though the base Stage 3 kit software targets a conservative 550–570 hp on 93-octane fuel.

Intercooler and Charge Air System

Higher boost pressures generate substantial heat, and the stock intercooler quickly becomes a bottleneck. The APR kit includes a high-capacity air-to-water intercooler that is larger and more efficient than the factory unit. This upgrade reduces intake air temperatures (IATs) by as much as 20–30°F under sustained load, maintaining consistent power during back-to-back pulls. The kit also replaces the stock charge pipes with larger-diameter, smoother-flowing units to minimize pressure drop. Together, these components keep the intake charge cool and dense, which is essential for knock-free performance.

Fuel System Upgrades

Stock fuel injectors and pumps can run out of headroom above 500 hp. APR addresses this with a set of larger injectors and a high-pressure fuel pump (HPFP) upgrade. The injectors flow enough fuel for 550+ hp on pump gas, and the HPFP maintains sufficient rail pressure under high load. For owners who plan to push beyond 600 hp (e.g., with E85 or race fuel), additional fuel system modifications like port injection may be required, but the included components are sufficient for the kit’s stated power range.

ECU Calibration and Tuning

No turbo upgrade is complete without proper software. APR provides a full ECU flash that recalibrates boost targets, fuel timing, vanos adjustments, and torque limits. The tune is available for both 93-octane and 91-octane pump gas, and an optional 100-octane map can be unlocked for track days. APR’s calibration is known for its conservative safety margins – they prioritize long-term reliability over max peak power. The Stage 3 tune also integrates all safety systems, including knock sensors and temperature protection, so the engine operates within safe limits.

External resource: APR’s official website provides detailed specs and ordering information for the M2 Competition Stage 3 kit.

Installation Process and Considerations

Installing a Stage 3 turbo kit is not a weekend driveway project for the faint of heart. While APR designed the kit to be as close to a direct bolt-on as possible, the complexity of the S55 engine bay and the need to remove many factory components means professional installation is strongly recommended. The following outlines the general steps and considerations.

Professional Installation vs. DIY

We recommend having the kit installed by a shop experienced with BMW S55 engines, particularly one that has performed APR Stage 3 upgrades before. The labor involves disassembling the intake manifold, removing the factory turbo and intercooler, replacing coolant and oil lines, and installing the new components. A DIY enthusiast with a well-equipped garage and a lift can potentially complete the job, but the risk of incorrect installation (e.g., improperly torqued clamps, misaligned oil feeds) can lead to turbo failure or engine damage. Most shops will also perform the ECU flash as part of the installation, ensuring a seamless integration.

Estimated Labor and Time

Labor costs vary by geographic region and shop rate. A reputable independent BMW tuner may charge $100–$175 per hour, and the total installation can take 14–20 hours depending on the technician’s familiarity with the vehicle. That translates to an additional $1,400–$3,500 in labor. Some specialized shops offer package deals that include the kit plus installation at a bundled price. It’s wise to get a firm quote before committing.

Required Supporting Mods

While the APR Stage 3 kit includes the critical components, there are several supporting modifications that should be considered for optimal results and reliability:

  • Upgraded intercooler diverter valve or blow-off valve: The factory valve may not hold added boost pressure. APR offers a billet diverter valve as an optional upgrade.
  • Spark plugs: Step-colder spark plugs are recommended to prevent pre-ignition under higher boost. APR specifies a specific NGK plug gap and part number.
  • High-flow intake: The kit assumes you have an aftermarket intake (such as APR’s own carbon intake) to allow the turbo to breathe. If not already equipped, budget $400–$600.
  • Upgraded intercooler reservoir and pump (optional): For sustained track use, a larger intercooler reservoir and higher-flow electric pump can further reduce heat soak.
  • Transmission and clutch upgrades: The M2 Competition’s 7-speed DCT can handle 550 hp with a software torque reduction in lower gears, but a manual transmission car will almost certainly require a stronger clutch. Budget $800–$2,000 for a clutch upgrade.

Performance Metrics and Real-World Gains

The primary reason owners invest in Stage 3 is the dramatic increase in power and response. On a properly installed kit with the correct software and supporting mods, results are impressive.

Dyno Results

On a chassis dynamometer, the M2 Competition with APR Stage 3 typically puts down 520–550 whp (wheel horsepower) and 520–560 lb-ft of torque on 93-octane. That’s a gain of roughly 150 whp over a stock car. With a 100-octane tune, numbers can climb to 570–590 whp. For reference, stock S55-powered M2 Competition dyno around 370–390 whp. The torque curve peaks near 4,000 rpm and stays flat to redline, providing strong mid-range punch.

External resource: A detailed dyno graph and comparison can be found at BimmerTuning (example – replace with real source). Many forums like M2C FB groups post user dyno sheets as well.

Acceleration and Top Speed

With 550+ whp, the M2 Competition can accelerate from 0–60 mph in the low 3-second range (with a good launch) and rip through the quarter-mile in roughly 11.0 seconds at 125+ mph. Trap speeds exceed those of a stock Porsche 991.1 Carrera S. Highway passing response becomes violent; a 60–130 mph pull can be achieved in under 8 seconds. The car pulls hard well past 150 mph, though aerodynamic drag limits top speed to around 180 mph unless gearing changes are made.

Reliability at 550+ HP

The S55 engine is robust, and with APR’s conservative calibration, many owners report tens of thousands of trouble-free miles on Stage 3. That said, increased power places more stress on the transmission, differential, and cooling system. It is essential to monitor oil temperatures and to allow adequate cool-down periods after aggressive driving. A high-quality synthetic oil change every 5,000 miles is recommended. Some owners also add a larger auxiliary oil cooler for track duty. If you push the car on a road course, be prepared to upgrade brakes and brake fluid as well.

Cost Breakdown: Beyond the $3,800 Kit

The APR Stage 3 kit itself is $3,800, but the total investment to reach 550+ hp reliably is higher. Here’s a realistic budget breakdown for a complete Stage 3 conversion on an M2 Competition:

  • APR Stage 3 turbo kit: $3,800
  • APR carbon intake (if not already installed): $500
  • Spark plugs (set of 6, colder step): $100
  • Diverter valve upgrade: $150
  • Professional labor (14–20 hours): $1,800–$3,500
  • ECU flash (included with kit, but labor for programming may be extra): $0 if done by shop
  • Clutch upgrade (manual transmission only): $1,200–$2,000
  • Cooling system upgrades (optional but recommended for track): $800–$2,000
  • Miscellaneous fluids, gaskets, and hardware: $200–$400

Total estimated cost: Roughly $8,000–$12,000 depending on options and labor rates. That’s considerable but reflects the transformation from a 405 hp car to a genuine 550+ hp performance machine.

Ongoing Maintenance Costs

With greater power comes more frequent wear. Budget for more oil changes (every 5,000 miles), spark plug replacement every 20,000 miles, and differential fluid changes every 30,000 miles. Turbocharged cars also benefit from intercooler system flushes every 2–3 years to prevent corrosion. Tires will wear faster with the added torque; expect rear tire replacement every 8,000–12,000 miles with aggressive driving. Overall, add about $500–$800 per year in incremental maintenance costs.

Comparison with Other Stage 3 Options

The APR Stage 3 kit is not the only big-turbo solution for the M2 Competition. Other well-known offerings include:

  • Pure Turbos Stage 2+ (PWG/EWG): Pure offers a hybrid turbo upgrade that uses the factory housings but with larger internals. It’s less expensive (around $2,500) but requires custom tuning and typically maxes out around 520 whp. Installation is simpler but still complex.
  • Vargas Turbo Technologies (VTT) GC Lites: These are in-frame turbos that produce similar power to APR Stage 3 but at a lower price point (~$3,000). However, reliability reports have been mixed, and customer support varies.
  • Mosselman Twin-Turbo Kit: A full twin-scroll setup that can support 600+ whp, but it’s significantly more expensive ($5,000+ kit, very labor-intensive) and requires extensive supporting mods including a stand-alone engine management system.

APR’s advantage lies in its turn-key nature and warranty support. The kit is sold as a complete package with matched software, and APR has a strong network of dealers. For the M2 Competition owner who wants a proven, reliable 550+ hp solution without extensive fabrication, the APR Stage 3 kit is the gold standard.

External resource: A forum comparison thread can be found on BimmerPost (search “M2C stage 3 turbo comparison”).

Conclusion

The APR Stage 3 Turbo Upgrade Kit offers a comprehensive, reliable path to 550+ horsepower for the BMW M2 Competition. At $3,800 for the core hardware, it represents a solid value for the power gain, though total investment with installation and supporting modifications typically falls between $8,000 and $12,000. The kit transforms the M2 Competition into a car that can hang with supercars costing three times as much, while retaining daily-driver civility when driven gently.

For any M2 Competition owner who has already addressed suspension and brakes and is hungry for more straight-line performance, the APR Stage 3 kit is a proven, well-engineered upgrade. As with any major modification, work with a reputable installer, follow the recommended maintenance schedule, and enjoy one of the most rewarding driver’s cars available today.