The Lexus IS has long been a favorite among driving enthusiasts who refuse to choose between luxury and performance. With its rear-wheel-drive chassis, refined interior, and available V6 power, the IS platform offers a solid foundation for serious upgrades. While the factory output of the IS 350 (around 311 horsepower) is respectable, many owners aim for the 400-horsepower milestone and beyond. Achieving this requires a systematic approach: forced induction, supporting modifications, and chassis upgrades to handle the added power. This comprehensive guide covers turbocharging and suspension modifications to transform your Lexus IS into a 400+ horsepower machine without sacrificing daily drivability.

Understanding Your Lexus IS Platform

Before purchasing any parts, you must identify your specific model and engine. The Lexus IS has been offered with several powertrains, and each responds differently to modifications. The most common performance-oriented models are the IS 200t, IS 300, and IS 350 across the second and third generations (2006–2013 and 2014–present).

Engine Options and Starting Points

  • IS 200t (2.0L turbocharged inline-4, 8AR-FTS): This model already has a turbocharger from the factory, making it easier to reach 400 hp with a larger turbo, upgraded intercooler, and proper tuning. However, the smaller displacement means you’ll be pushing higher boost levels to match the V6’s potential.
  • IS 300 (3.5L V6, 2GR-FSE or 2GR-FKS): The naturally aspirated V6 in the IS 300 is a strong base. With a turbo kit (or supercharger), 400–450 hp is achievable on a stock bottom end. The 2GR-FSE (direct injection) requires careful fuel system planning.
  • IS 350 (3.5L V6, 2GR-FSE or 2GR-FKS): The higher-compression version in the IS 350 delivers 311 hp stock. With a well-designed turbo system and supporting modifications, 450+ hp is common. The forged internals of the 2GR-FSE are robust, but proper tuning is essential to avoid detonation.

Chassis Differences

The second-generation IS (XE20) uses a double-wishbone front suspension and a multilink rear, while the third-generation (XE30) shares the New N platform with the GS and RC. Both benefit from upgraded dampers, springs, and sway bars, but parts compatibility varies. Always verify part fitment with your model year.

Turbocharging Your Lexus IS for 400+ Horsepower

Turbocharging is the most effective method to add significant horsepower to the naturally aspirated V6 engines. For the IS 200t owners, upgrading the stock turbo and adding supporting mods is the path to 400 hp. We’ll focus on the V6 platforms here, as they offer the greatest potential.

Choosing a Turbo Kit

A complete bolt-on turbo kit simplifies the process. Look for kits specifically designed for the 2GR-FE/2GR-FSE engine family in the Lexus IS. Key considerations include turbo size, exhaust manifold design, and included components. Popular kits from reputable manufacturers include:

  • Greddy Turbo Kit for 2GR-FSE: Known for quality cast manifolds and a ball-bearing GTX3071R turbo, this kit supports up to 500 hp. It includes intercooler piping, a blow-off valve, and wastegate.
  • HKS Turbo Kit: Offers a bolt-on solution with a GTII-SS turbocharger. The kit is CARB-legal (EO number) for some model years, which is critical for emissions compliance.
  • VIP Modular Turbo Kit: A custom fabrication option that can be tailored to your power goals. These typically use a Precision or Garrett turbo and require a supporting fuel system.

When selecting a kit, ensure it includes an intercooler, oil and coolant lines, and all necessary gaskets. A standalone engine management system (like a Haltech or Motec) is often recommended for tuning flexibility, though some kits work with ECU flash tunes.

Supporting Fuel and Engine Modifications

Adding a turbo without upgrading the fuel system is a recipe for failure. The direct injection (DI) system in the 2GR-FSE can run out of capacity around 400–450 hp. Consider these upgrades:

  • High-flow fuel injectors: Port-injection add-on kits (such as the ones from Injector Dynamics or Fuel Injector Clinic) supplement the DI system, providing additional fuel for high boost.
  • Upgraded fuel pump (or dual pumps): The stock in-tank pump may not supply enough volume. A Walbro 450 or equivalent drop-in unit is common, or a surge tank with external pumps for extreme builds.
  • Intercooler upgrade: A larger air-to-air intercooler reduces intake air temperatures, preventing heat soak on repeated pulls. Look for a core size appropriate for your power level (around 600 hp capacity is sufficient).
  • Exhaust system: A 3-inch downpipe and cat-back exhaust minimize backpressure. Avoid cheap “cat-back” that does not accommodate the increased flow. A high-flow catalytic converter (or a test pipe for off-road use) can net 10–15 whp.

Installation Process

Installing a turbo kit is a multi-day project for a well-equipped DIYer. The general steps are:

  1. Prepare the engine bay: Disconnect the battery, drain coolant and oil, and remove the air intake, exhaust manifolds, and front bumper (for intercooler access).
  2. Install the turbo manifold and turbocharger: Use new gaskets and stainless steel nuts. Ensure all oil and coolant lines are properly routed and secured away from heat sources.
  3. Mount the intercooler and charge pipes: Secure it to the crash bar or core support. Use silicone couplers and T-bolt clamps to prevent boost leaks.
  4. Install the wastegate and blow-off valve: Connect vacuum lines to the boost source. Adjust the wastegate spring pressure to match your target boost.
  5. Fuel system modifications: Install new injectors, pumps, and fuel pressure regulator if required. Double-check all electrical connections.
  6. Engine management: Wire in the standalone ECU or ship your stock ECU for a flash tune. This is the most critical step for safety.

Tuning for Reliability and Power

A professional dyno tune is essential. Even if you purchase a “pre-tuned” kit, local fuel quality and climate variations demand custom calibration. Experienced tuners for the 2GR-FSE include TurboSource and MotoIQ. Tuning parameters include:

  • Ignition timing: Reduce timing under boost to prevent knock. Aim for a safe margin (e.g., 10–12 degrees BTDC at peak torque).
  • Air-fuel ratio (AFR): Target 11.5–12.0:1 under full boost to ensure rich fuel cooling.
  • Boost control: Use an electronic boost controller for precise boost levels. Start conservative (6–8 psi) and gradually increase while monitoring knock counts.

With a proper tune and supporting mods, a Lexus IS 350 running 10–12 psi of boost can safely make 420–450 whp (around 480–520 hp at the crank).

Suspension Modifications for High-Performance Handling

Adding 200+ horsepower to the chassis requires complementary suspension upgrades. A soft, wallowing suspension will make the car unpredictable and unsafe at speed. Prioritize handling mods that improve stability, reduce body roll, and maintain consistent geometry.

Coilovers vs. Lowering Springs

For a car that will see track days or aggressive street driving, coilovers are the superior choice. They offer adjustable damping and ride height, allowing you to balance comfort and performance. Recommended coilover brands for the Lexus IS include:

  • KW Variant 3: Independent compression and rebound adjustment. These are a favorite for daily-driven track cars due to their premium valving.
  • BC Racing BR Series: A cost-effective option with 30-click damping adjustment and a two-year warranty. Suitable for street and occasional track use.
  • Ohlins Road & Track: For the ultimate in handling, these inverted struts provide incredible grip and bump absorption. They are pricey but well worth it.

If you prefer a mild drop without sacrificing too much ride quality, Eibach Pro-Kit or H&R Sport Springs can lower the car by 1–1.5 inches and reduce body roll. However, they require matching performance shocks (like Bilstein B8) for optimal damping.

Upgraded Sway Bars

Sway bars (anti-roll bars) are one of the most cost-effective handling upgrades. Stock bars are designed for comfort; thicker bars transfer load more effectively, keeping the car flatter in corners. Consider these options:

  • Whiteline Sway Bars: Adjustable in strength (two-hole design), allowing you to fine-tune oversteer/understeer balance.
  • Hotchkis Sway Bars: Available in hollow or solid construction. The front bar is typically 32mm, rear 22mm.
  • ST Suspensions Sway Bars: A budget-friendly brand that partners with KW, offering a 28mm front and 20mm rear set.

Installation is straightforward: remove the stock bars, replace the end links (upgrade to adjustable aluminum links for better connection), and torque to spec. A stiffer rear bar can induce rotation, making the car more playful at the limit.

Chassis Bracing and Bushings

To keep the chassis planted under hard acceleration and braking, add bracing where the suspension mounts. Popular items include:

  • Front strut tower bar: Reduces chassis flex in the engine bay.
  • Rear subframe brace: Prevents the rear differential from moving under load, improving traction.
  • Polyurethane bushings: Replace worn rubber control arm and sway bar bushings. Energy Suspension and Whiteline offer complete bushing kits. The downside is increased NVH (noise, vibration, harshness), but the handling payoff is substantial.

Alignment Settings for Performance

After lowering and installing sway bars, get a proper alignment to optimize tire contact patch. A street-performance alignment might be:

  • Camber: 1.5–2.0 degrees negative front, 1.0–1.5 degrees negative rear (depending on lowering and tire width).
  • Caster: As much positive caster as possible (6–7 degrees) for straight-line stability.
  • Toe: 1/16-inch toe-in rear, 1/16-inch toe-out front for turn-in response. Or zero toe for even tire wear.

Additional Performance Considerations

Tires and Wheels

All the power and suspension upgrades are useless without proper tires. For a 400+ hp IS, consider 18- or 19-inch wheels with high-performance summer tires such as the Michelin Pilot Sport 4S or Toyo Proxes R888R. Minimum width: 8.5 inches front, 9.5 inches rear. A staggered setup (e.g., 235/40R18 front, 265/35R18 rear) provides adequate grip.

Brake Upgrades

Stopping power must match your speed increases. At minimum, upgrade to high-performance brake pads (e.g., Carbotech XP8 or Hawk HP+) and slotted rotors. For track use, consider a big brake kit (BBK) from StopTech or Brembo with 6-piston calipers and 355mm rotors. Brake cooling ducts are also beneficial.

Maintenance and Reliability After Upgrades

A boosted Lexus IS demands more frequent maintenance. Plan for:

  • Oil changes every 3,000 miles with high-quality synthetic (e.g., Motul 300V) to protect the turbo bearings.
  • Spark plugs every 20,000 miles (one step colder for boosted engines).
  • Coolant flush annually to prevent corrosion and ensure proper heat rejection.
  • Boost leak test every 6 months using a smoke machine to find splits in silicone hoses.
  • Suspension component inspection: Ball joints, tie rods, and bushings wear faster with stiffer springs and wider tires.

Conclusion: Enjoy the Build Journey

Building a 400+ horsepower Lexus IS is a rewarding project that transforms a luxury sedan into a genuine sport machine. Start with a solid understanding of your engine and chassis, invest in a quality turbo kit (including all supporting mods), and pair it with a well-sorted suspension. Don’t cut corners on tuning or installation—reliability is paramount. With careful planning, your upgraded IS will be a thrilling daily driver or a capable track car that stands out from the crowd. Begin your build with research from trusted sources like the Lexus Owner’s site and enthusiast forums, and enjoy every step of the process.