The VTT Stage 2 Turbo Upgrade for the BMW S63 engine is one of the most effective bolt-on modifications for owners seeking a serious increase in power. By replacing the factory twin-turbochargers with larger, more efficient units, this upgrade reliably pushes output past 650 horsepower while maintaining drivability and engine integrity. For enthusiasts who have already addressed basic bolt-ons and tuning, the VTT Stage 2 package represents a well-documented path to supercar-slaying performance. This article provides a complete technical breakdown of the upgrade, covering installation, costs, real-world gains, and key considerations for prospective buyers.

The S63 Engine: A Twin-Turbo Marvel

Introduced in 2009, BMW’s S63 is a twin-turbocharged 4.4-liter V8 that powers the brand’s most aggressive M models. Found in the M5 (F10, F90), M6, X5 M, X6 M, and later M8 Competition variants, this engine is a masterpiece of forced induction. The block uses a cross-bolted main bearing design and a closed-deck construction to withstand high cylinder pressures. Factory output ranges from 560 to 625 horsepower depending on the model and year, but the engine’s architecture was designed with headroom from the start.

The S63 uses two Mitsubishi heavy-duty TD03 turbochargers positioned in the V-bank, each feeding one bank of cylinders. This layout keeps the intake path short and response crisp, but the small turbine housings limit top-end air flow. At a factory boost level around 14–16 psi, the turbos are already working near their efficiency limit. The VTT Stage 2 upgrade addresses this bottleneck by replacing the factory units with larger, purpose-built turbos that flow significantly more air at the same or slightly higher boost pressure.

Understanding the S63’s Airflow Limits

To unlock 650 wheel horsepower, you need roughly 65–70 lb/min of total compressor flow. The stock turbos peak around 48–52 lb/min before they become heat-soaked and require excessive boost to deliver any additional air. Larger compressor wheels with extended tip designs, combined with upgraded turbine wheels and housings, allow the engine to ingest more air with lower exhaust backpressure. This is precisely what the VTT Stage 2 kit delivers.

What Makes the VTT Stage 2 Upgrade Different

Vargas Turbo Technologies (VTT) has been a dominant player in the BMW forced-induction aftermarket for over a decade. Their Stage 2 kit for the S63 is not simply a rebranded factory turbo with a ported housing. It uses fully billet compressor wheels, upgraded thrust bearings, and custom-machined compressor housings to increase flow capacity without sacrificing spool time. The kit is designed to be a direct bolt-on replacement, meaning no major modifications to the exhaust system, oil lines, or coolant lines are required, though supporting upgrades are strongly recommended.

Key Components of the Kit

  • Billet Compressor Wheels: Each turbo features a larger, custom aero profile billet wheel that flows approximately 30–35% more air than the stock cast wheel. The specific indesigner geometry reduces turbulence and improves compressor efficiency at high boost levels.
  • Upgraded Turbine Wheel: The turbine wheel is made from a higher-temperature Inconel equivalent to handle the increased exhaust gas temperatures that come with more power. A slightly larger trim helps maintain boost without spiking backpressure.
  • Reinforced Actuator System: The wastegate actuators are upgraded to prevent boost creep. They are pre-set to hold boost levels up to 22–24 psi without oscillation, which is essential for consistent power delivery.
  • High-Flow Intake Inlets (optional): While the base kit uses the factory intake piping, VTT recommends their silicone inlets to reduce restriction and improve airflow to the compressor covers.

How It Stacks Up Against Other Stage 2 Options

Several vendors offer S63 Stage 2 upgrades, but VTT differentiates itself by focusing on plug-and-play compatibility with factory engine management and driveline components. Their turbos also feature a ceramic ball-bearing center section for faster spool and longer life compared to journal-bearing alternatives. Independent dyno tests on the F10 M5 platform show the VTT Stage 2 reaching peak boost around 3,200 RPM, only 200–300 RPM later than stock, which is excellent given the power increase.

Installation: A Step-by-Step Process

Installing the VTT Stage 2 turbos is an involved job that requires mechanical experience and specialized tools. The average garage cannot complete this swap in a weekend; most shops estimate 20–25 labor hours for a first-time install. The procedure follows a logical but meticulous sequence:

  1. Disassembly of the hot side: Drain coolant and oil, remove the air filter boxes and intake ducts, disconnect the charge air cooler piping, and unbolt the downpipes from the turbine outlets. The heat shields and valve covers must also come off to access the turbo mounting bolts.
  2. Removal of the factory turbos: Unbolt the four exhaust manifold-to-turbo fasteners, disconnect oil feed and return lines (with crush washers replaced), and carefully lift each turbocharger out of the V-bank. The rear turbo is more difficult due to limited clearance.
  3. Prepping the new turbos: Transfer any necessary spacers or brackets from the old units. Prime the oil passages by filling the feed port with clean engine oil, and rotate the compressor wheel manually to ensure free movement.
  4. Installation of new turbos: Position each VTT turbo into its mounting location, align the exhaust manifold studs, and torque all hardware to factory specifications. Reconnect the oil and coolant lines with new seal washers. The wastegate actuators must be adjusted so the preload matches the kit instructions (typically 2–3 mm of arm travel).
  5. Reassembly and check: Reinstall the intake ducting, downpipes, heat shields, and valve covers. Fill coolant and oil, then start the engine and check for leaks. A proper test drive with data logging is mandatory to adjust boost targets through the tune.

Pre-Installation Considerations

Supporting modifications are essential. At 650 HP, the stock fuel system in early S63 engines (pre-2015) will run out of headroom. Upgraded low-pressure fuel pumps and high-pressure injection components may be required. Also, the charge air coolers should be upgraded to manage intake air temperatures; VTT recommends their Stage 1 intercooler package or equivalent. A set of high-performance downpipes with 200-cell catalytic converters or catless designs is typically paired with this turbo kit to reduce backpressure further. Finally, a methanol injection kit can provide insurance against detonation and allow more aggressive timing.

The Tuning Factor

No turbo upgrade operates without a custom calibration. The factory ECU uses a torque-based load control system that will adapt to larger turbos up to a point, but to safely hit 650 HP you must run an aftermarket tune from a reputable tuner like DME Tuning, Bootmod3, or ECUTek. The tune adjusts boost targets, wastegate duty cycles, timing, and fuel trims. Most tuners target a peak boost of 20–22 psi on 93 octane gasoline, or up to 24 psi with an ethanol blend (E30–E50). The tune also changes the VANOS variable valve timing to optimize spool and top-end flow.

Cost Breakdown and Budgeting

The total cost of a VTT Stage 2 upgrade varies by vehicle condition, location, and choice of supporting parts. Below is a realistic estimate for a typical installation on an F10 M5 or F15 X5 M:

  • VTT Stage 2 Turbo Kit: $3,795 – $4,495 (depending on inlet pipe options)
  • Labor for removal and installation: $1,500 – $2,500 at a specialty shop
  • Custom tuning: $600 – $1,200 (includes dyno time or remote calibration)
  • Supporting parts (recommended): $1,000 – $2,500 (downpipes, inlets, intercooler, fuel pump, spark plugs one step colder)
  • Miscellaneous gaskets and fluids: $150 – $300

A fully engineered install with all supporting mods and tuning can reach $8,000 – $11,000. While that may seem steep, the result is a reliable 650-HP build that retains full drivability. Many owners report that this upgrade costs significantly less than a supercharger system while delivering similar peak power with better throttle response.

Hidden Costs to Consider

If you are pushing higher boost, the stock plastic charge pipes can crack. Upgraded aluminum charge pipes are a wise investment ($300–$500). Also, the transmission (ZF 8HP automatic) may require an increased line-pressure tune or a torque converter upgrade if you frequently drag race. Be prepared for potential clutch pack wear at power levels above 600 HP.

Performance Gains: From Factory to 650 HP

Verified dyno sheets from multiple installations show that the VTT Stage 2 kit, combined with 93 octane fuel and a conservative tune, produces 645–665 whp and 680–720 lb-ft of torque. Compared to a factory S63 that typically dynos around 480–510 whp (depending on drivetrain losses), the gain is approximately 150–170 whp. On an E30 blend, numbers increase to 690–710 whp and 760 lb-ft. These are wheel figures; at the crank, the engine is producing around 750–800 horsepower.

Acceleration and Quarter-Mile Performance

  • 0–60 mph: 2.9 – 3.2 seconds (with sticky tires and proper launch control)
  • Quarter-mile: 10.4 – 10.8 seconds at 130–135 mph
  • 60–130 mph: 7.5 – 8.2 seconds, a dramatic improvement over stock (10–11 seconds)

The increase in mid-range torque is the most noticeable change. At 3,500 RPM, the VTT Stage 2 delivers roughly 600 lb-ft of torque, compared to 450 lb-ft stock. This makes highway merging and rallying the throttle at legal speeds a ferocious experience. The turbos reach full boost by 3,400 RPM, so there is very little lag compared to larger single-turbo conversions.

Driving Character Changes

Beyond the numbers, the drive quality remains civilized. The wastegate actuators are sequential, so part-throttle cruising produces minimal spool noise and the car feels docile. Once the accelerator is flattened, the engine responds with a deep, aggressive tone from the upgraded turbos. Many owners report that the power delivery is linear rather than a sudden spike, which aids traction in the wet.

Reliability and Longevity

The S63 engine is robust, but pushing very high boost (above 22 psi) for extended periods places stress on the piston rings and rod bearings. The VTT Stage 2 upgrade stays well within the safe envelope for a properly maintained street engine as long as supporting modifications are in place. Key reliability factors:

  • Oil quality and volume: Use 5W-50 full synthetic oil and keep the fill level slightly above the center mark. The turbos draw oil from the engine’s main gallery; restricted supply will cause bearing failure.
  • Heat management: The larger turbine housings shed heat more effectively than factory units, but water-methanol injection is recommended for sustained high-load driving (e.g., track days or mountain pulls).
  • Boost control: Do not run the turbos past 24 psi without ethanol or race fuel. The knock threshold narrows significantly at higher boost on pump gas.
  • Annual checks: Inspect oil return lines for kinks, verify wastegate arm free play, and perform a compression test each year to catch issues early.

When properly tuned and maintained, VTT Stage 2 turbos have logged over 50,000 miles on several owner builds without failure. The ceramic ball-bearing core is significantly more resistant to thermal cycling wear than the factory journal bearings.

Comparing VTT Stage 2 vs. Other Upgrades

Many owners wonder whether to step up to a Stage 3 kit or go a different route. Here is a brief comparison:

  • Stock turbos + tune: Yields about 580–600 hp at the crank. Cheap but leaves a lot on the table.
  • VTT Stage 1 hybrid: Uses modified factory turbos with larger wheel. Reaches ~620 hp but spool is nearly identical to stock. Cost is $2,500–$3,000.
  • VTT Stage 2 (this article): 650+ whp, retains factory fitment, best balance of cost and power.
  • VTT Stage 3 / GC Lites: Huge billet turbos that can exceed 800 whp. Requires upgraded fuel system, built bottom end, and aggressive cams. Cost is $8,000–$12,000 for turbos alone, plus massive labor.
  • Single turbo conversion: A 72 mm or 85 mm single unit. Increases lag significantly, but peak power can exceed 1000 hp. Not a street-friendly choice.

The VTT Stage 2 is the sweet spot for enthusiasts who want reliable, high-triple-digit horsepower without sacrificing daily usability.

Final Verdict

The VTT Stage 2 Turbo Upgrade is one of the most thoroughly engineered and proven modifications for the BMW S63 engine. It unlocks genuine 650 horsepower with a direct bolt-on approach, minimal change in boost threshold, and a robust hardware design backed by years of aftermarket experience. The costs are significant, but the result is a transformation: your M5, M6, X5 M, or M8 becomes a car that can embarrass supercars costing twice as much, all while retaining full interior comfort and factory-like reliability when properly supported. For any serious S63 owner, this upgrade should be at the top of the list.

For further reading on tuning strategies and install tips, consult the reputable VTT official website and the F10 M5 forum for owner builds and dyno database threads.