Intro
The Subaru Legacy B4 RSK emerged at the turn of the millennium as a performance-oriented variant of Subaru’s respected Legacy line. Released exclusively in Japan in 2000, this twin-turbo sedan represented Subaru’s commitment to blending practical four-door design with potent performance capabilities during an era when Japanese manufacturers were creating some of their most innovative vehicles.
Within JDM culture, the Legacy B4 RSK holds significance as an underappreciated gem in Subaru’s performance lineup. While the WRX and STI variants have dominated Western attention, the Legacy B4 RSK earned devoted followers for its sophisticated approach to performance, offering the rally-bred drivetrain technology in a more mature, executive package. Its twin-scroll turbo EJ20 engine and sophisticated all-wheel-drive system embodied Japan’s golden era of performance engineering.
This particular build stands out for its meticulous balance between period-correct modifications and modern performance enhancements. Unlike many heavily modified examples that have strayed from their original character, this RSK preserves the distinctive Subaru driving experience while thoughtfully addressing the platform’s known limitations. It represents a carefully executed vision of what Subaru’s engineers might have created had they continued evolving the B4 RSK beyond its initial production.
Builder Profile
Takeshi Yamamoto, a 35-year-old aerospace engineer from Yokohama who relocated to Southern California in 2015, approaches his Subaru builds with precision derived from his professional background. His tuning philosophy centers on achieving the perfect balance between daily drivability and track performance, refusing to sacrifice reliability for fleeting power gains.
Yamamoto’s meticulous nature is evident in his Legacy B4 RSK build, where every modification serves a specific purpose. He’s become a respected fixture in the SoCal Subaru community, organizing technical workshops for enthusiasts and participating in local time attack events.
While many chase the latest trends, Takeshi maintains that understanding the engineering fundamentals behind each modification matters more than following the crowd. His builds reflect this thoughtful approach—subtly aggressive yet thoroughly functional.
Why We Love It
In the pantheon of JDM excellence, the Legacy B4 RSK represents Subaru at its most sophisticated yet uncompromising. While the WRX STI grabbed headlines with rally heroics, the B4 RSK cultivated a more nuanced character—a gentleman’s express cloaked in purposeful anonymity.
The twin-scroll turbocharger mated to the EJ206 delivers power with a distinctive urgency above 3500rpm, eliminating the laggy characteristics of its contemporaries. Its chassis dynamics speak to Subaru’s obsession with handling balance; the symmetrical AWD system distributes torque with an almost prescient understanding of driver intent, particularly evident when powering through Japan’s mountain passes where camber changes test lesser platforms.
What truly distinguishes the RSK is its motorsport lineage translated through a filter of restraint. The model inherits the New Zealand rally-spec Legacy’s spirit while integrating luxuries absent in the Impreza lineup. Its rarity—particularly in unmolested form—offers a glimpse into Subaru’s engineering philosophy before the brand’s eventual pivot toward mainstream acceptance.
The RSK exemplifies peak late-90s Japanese engineering: complex, overbuilt, and designed without the compromises that would later define the industry’s approach to performance sedans. It’s not merely a car we appreciate—it’s automotive evidence of an era when driving dynamics weren’t negotiable.
Mods
ENGINE & DRIVETRAIN
- HKS Super Sequential Blow-Off Valve
- Tomei Expreme Ti Titanium Exhaust System
- Trust/GReddy Front-Mount Intercooler
- NGK Iridium Spark Plugs
- ARC Intake Box with K&N Filter
- Samco Silicone Hoses (Blue)
- Cusco Oil Catch Can
- STI Pink Injectors (550cc)
- Koyo Aluminum Radiator
- Exedy Stage 2 Clutch Kit
SUSPENSION & BRAKES
- Cusco Zero-A Coilovers
- Cusco Front & Rear Strut Bars
- Whiteline Anti-Roll Kit
- AP Racing 4-Piston Front Calipers
- Project Mu HC+ Brake Pads
- Goodridge Stainless Brake Lines
- KAAZ 1.5-Way Limited Slip Differential
- Cusco Underbody Brace Set
WHEELS & TIRES
- Volk Racing TE37 18×8.5 +35 (Gunmetal)
- Yokohama Advan Neova AD08 225/40R18
- Project KICS R40 Lug Nuts (Neo Chrome)
- H&R 15mm Wheel Spacers (Rear)
EXTERIOR / AERO
- Chargespeed Bottom Line Body Kit
- STI Front Lip Spoiler
- OEM JDM Fog Light Kit
- APR Carbon Fiber GT Wing
- Seibon Carbon Fiber Hood
- JDM Rain Guards
- C-West Carbon Fiber Trunk
- HID Xenon Headlight Conversion
INTERIOR
- Bride Zeta III Seats (Black/Blue)
- Takata 4-Point Harnesses
- Personal Neo Grinta Steering Wheel (350mm)
- Works Bell Quick Release
- ARC Titanium Shift Knob
- STI Pedal Set
- Defi Advance BF Gauges (Boost, Oil Pressure, EGT)
- Nardi Shift Boot (Black Leather)
- Cusco Bolt-in Roll Cage
ELECTRONICS / ECU
- COBB AccessPORT V1
- Blitz SBC i-D Boost Controller
- Apexi Power FC + Commander
- Kenwood DDX9019S Head Unit
- Alpine PDX-V9 5-Channel Amplifier
- JL Audio W6v2 10″ Subwoofer
- Focal K2 Power Component Speakers
- Pivot 3-Drive Throttle Controller
- HKS Turbo Timer
Driving Impression / Build Philosophy
The 2000 Legacy B4 RSK build represents a carefully orchestrated blend of modifications that prioritize balanced performance while maintaining daily driveability. Each component has been selected to complement the others, creating a cohesive package rather than a collection of mismatched parts.
The foundation begins with the mild power upgrades that enhance the EJ20’s output without sacrificing reliability. These power gains are properly supported by upgraded braking components and suspension refinements that guarantee the chassis can effectively manage the additional performance. The combination of STI-sourced Brembos and coilovers with properly calculated spring rates creates predictable handling characteristics without the harshness typically associated with track-focused setups.
This build philosophy clearly leans toward spirited street driving with occasional track day capability. The exterior modifications maintain the Legacy’s understated presence while subtly communicating its performance potential. Interior upgrades focus on the driver experience without sacrificing comfort or practicality for daily use.
What sets this build apart is its restraint—modifications were chosen with purpose rather than excess. The result is a B4 that honors Subaru’s original sporting intent while elevating the driving experience through thoughtful, complementary upgrades that work in harmony across all vehicle systems.
FAQ
How reliable is the 2000 Subaru Legacy B4 RSK?
The 2000 Legacy B4 RSK is generally reliable when properly maintained. The EJ208 twin-turbo engine can reach well over 200,000 kilometers with regular oil changes and timing belt service at recommended intervals. Compared to the more problematic EJ25 engines, the EJ208 tends to have fewer head gasket issues, though proper cooling system maintenance remains crucial.
What are the common issues with the Legacy B4 RSK?
Common problems include turbo failure (particularly the primary turbo), oil consumption in higher mileage examples, occasional automatic transmission failures, and deteriorating suspension bushings. The vacuum lines controlling the twin-turbo system often crack with age, causing inconsistent boost. Rust can be an issue on examples from northern regions, particularly around the rear wheel arches.
What is the tuning potential of the B4 RSK?
The EJ208 twin-turbo engine responds well to modifications, with 300-320hp achievable through bolt-on modifications without significant internal engine work. Popular upgrades include a front-mount intercooler, upgraded turbo, VF-30/VF-34 turbo swap, intake system, exhaust, and a proper ECU tune. With built internals, the platform can support 400+ horsepower.
What are the best first modifications for the Legacy B4 RSK?
Start with maintenance-oriented upgrades: replace aging vacuum lines, install a turbo timer, and ascertain the cooling system is in perfect condition. For performance, begin with a cat-back exhaust system, upgraded intake, and an aftermarket boost controller. A quality ECU tune will optimize these modifications and improve drivability.
How does the B4 RSK compare to the WRX of the same era?
The B4 RSK offers a more refined, mature driving experience compared to the more raw GC8 WRX. The Legacy provides better sound insulation, superior interior quality, and more luxury features, while still delivering impressive performance. The B4’s twin-turbo setup delivers smoother power delivery with less lag than the single-turbo WRX, though the WRX has a more extensive aftermarket support network.
What should I check when buying a used Legacy B4 RSK?
Inspect for service history, particularly timing belt and turbo replacements. Check for smooth operation of the twin-turbo system with no hesitation during acceleration. Verify the automatic transmission shifts cleanly without slipping. Look for signs of oil leaks around the valve covers and turbo banjo fittings. Compression and leakdown tests are advisable, as is inspection of the undercarriage for rust and collision damage.
Is the B4 RSK practical as a daily driver today?
Despite its age, the B4 RSK remains a practical daily driver with its all-wheel-drive system, comfortable cabin, and reasonable fuel economy (when driven conservatively). Parts availability can be challenging in some markets, and premium fuel is required. The sedan offers adequate trunk space and rear passenger room, making it more versatile than many performance cars while still delivering engaging driving dynamics.
Conclusion
The 2000 Subaru Legacy B4 RSK stands as a symbol of Japanese automotive engineering at its finest. Despite being over two decades old, this sedan continues to captivate enthusiasts with its perfect blend of practical performance and understated sophistication. Its twin-turbo boxer engine, symmetrical all-wheel drive, and driver-focused design philosophy represent the golden era of JDM sport sedans that offered genuine performance without sacrificing reliability or comfort.
In today’s automotive landscape dominated by electronic assists and turbocharged efficiency, the B4 RSK provides a more connected, mechanical driving experience that modern enthusiasts increasingly covet. Its rising status as a collectible underscores not just nostalgia, but appreciation for a time when driver engagement took precedence over convenience features.
For JDM aficionados, the B4 RSK embodies everything that made Japanese performance cars legendary: innovative engineering, exceptional build quality, and accessible performance that could be enjoyed daily. As an authentic piece of Japanese automotive culture, it continues to bridge generations of enthusiasts who recognize that while technology marches forward, the purity of purpose found in cars like the Legacy B4 RSK remains timeless.