Intro
The 2005 Subaru WRX STI Spec C represents the pinnacle of Japanese rally-bred engineering during Subaru’s golden era of motorsport dominance. Born from the company’s World Rally Championship success, this limited-production variant built upon the already formidable STI platform with focused performance enhancements.
In JDM culture, the Spec C commands reverence as a purist’s dream—a factory-built machine stripped of unnecessary weight and fortified for maximum driver engagement. It embodies the philosophy that defined Japan’s performance cars of the era: functional design, technological innovation, and the harmonious balance between everyday usability and track capability.
This particular build stands out for its preservation of the Spec C’s inherent character while thoughtfully enhancing its performance envelope. Rather than following trends or pursuing outlandish modifications, this example showcases a disciplined approach that honors the engineering intentions of Subaru’s motorsport division while addressing the platform’s few shortcomings.
Builder Profile
A 32-year-old aerospace engineer who splits his time between Tokyo and Seattle, Kazuo developed his passion for rally-inspired builds while working with composite materials for Boeing. His tuning philosophy centers on “functional precision” – every modification must serve a purpose while maintaining the vehicle’s reliability for both track days and weekend touge runs.
Kaz has become a respected figure in the Pacific Northwest Subaru community, organizing technical workshops and competitive time attack events. His engineering background enables him to develop custom solutions rather than simply installing off-the-shelf parts. He approaches each build with meticulous data collection, often creating spreadsheets to track performance changes after each modification.
While his STI remains his primary focus, Kaz occasionally consults for local tuning shops and has contributed technical articles to Import Tuner and DSPORT Magazine.
Why We Love It
The Spec C transcends mere automotive enthusiasm—it represents the purest engineering ethos of Subaru’s motorsport division. Where the standard STI serves as Subaru’s street-legal rally weapon, the Spec C strips away compromise with monastic dedication. Its 1,400kg curb weight—achieved through thinner glass, aluminum hood, and reduced sound deadening—creates a dynamic precision absent in its siblings.
What captivates most is the Spec C’s mechanical honesty. The strengthened six-speed transmission delivers crisper shifts through shorter ratios, while the revised DCCD (Driver-Controlled Center Differential) provides front-rear torque distribution that feels telepathic rather than electronic. The hydraulic steering communicates with an analog clarity lost in subsequent generations.
The specialized 2.0L EJ207 flat-four doesn’t chase headline power figures. Instead, it delivers torque with urgent immediacy thanks to a ball-bearing turbocharger and sodium-filled exhaust valves that manage heat more effectively. This engineering sophistication manifests in midrange response that rewards technical driving rather than straight-line heroics.
Its significance lies in its timing—released when homologation specials were becoming relics, the Spec C represents perhaps the last unfiltered expression of Subaru’s rally development program before emissions regulations and safety requirements diluted the rawness that defined these machines.
Mods
ENGINE & DRIVETRAIN
- HKS GT3037S turbocharger kit
- Tomei Expreme titanium exhaust system
- APS front-mount intercooler
- Samco silicone hose kit
- GReddy oil cooler
- Cusco oil catch can
- Exedy Hyper Single clutch kit
- Cusco limited-slip differential
- Cosworth high-flow fuel pump
- HKS Super Fire racing spark plugs
SUSPENSION & BRAKES
- Öhlins DFV coilovers
- Cusco front and rear strut braces
- Whiteline anti-roll bars
- Cusco lower arm bar
- Brembo 6-pot front calipers with 355mm rotors
- Project Mu racing brake pads
- Goodridge stainless steel brake lines
- Cusco master cylinder stopper
WHEELS & TIRES
- Volk Racing TE37SL 18×9.5″ +22 bronze
- Yokohama ADVAN Neova AD08 265/35R18
- Project Kics R40 lug nuts
- RAYS wheel locks
EXTERIOR / AERO
- Varis carbon fiber hood
- Varis carbon fiber front lip
- STI genuine side skirts
- Voltex Type 2 carbon rear wing
- HT Autos rear diffuser
- APR carbon fiber mirrors
- Craftsquare LED side mirrors
- PIAA HID conversion headlights
INTERIOR
- Bride Zeta III carbon kevlar seats
- Takata 4-point harnesses
- Personal Neo Grinta steering wheel
- Works Bell quick release hub
- STI titanium shift knob
- Cusco 6-point roll cage
- Defi gauge cluster (boost, oil pressure, water temp)
- Nardi shift boot
ELECTRONICS / ECU
- Cobb AccessPORT V2
- Haltech Platinum Pro ECU
- AEM wideband O2 sensor
- HKS EVC boost controller
- Blitz turbo timer
- Beatrush grounding kit
- Alpine head unit with Pioneer speakers
- AiM MXL Strada digital dash
Driving Impression / Build Philosophy
The 2005 Subaru WRX STI Spec C represents a cohesive package where every modification serves the car’s primary mission: delivering maximum performance on both circuit and backroads while maintaining daily usability. The lightweight components—carbon fiber hood, aluminum roof panel, and reduced sound deadening—work in harmony with the reinforced chassis to create a responsive platform that communicates clearly with the driver.
The balanced approach is evident in how power delivery matches the suspension setup. The engine’s improved throttle response from the modified ECU and exhaust system pairs perfectly with the tightened suspension geometry and upgraded Bilstein dampers. This synchronicity allows drivers to precisely modulate power through corners, making the car equally capable on technical track sections and flowing mountain roads.
Every modification follows a time attack philosophy where unnecessary weight is eliminated while structural rigidity is enhanced. The larger front-mount intercooler, improved braking system, and aerodynamic tweaks aren’t standalone showpieces but integral parts of a thorough performance vision. The result isn’t a collection of aftermarket parts but a purpose-built machine where each component complements the others in pursuit of maximum real-world speed and driver engagement.
Unlike pure show cars or dedicated competition vehicles, the Spec C maintains enough civility for street use while offering genuine track capability—a demonstration of Subaru Tecnica International’s engineering approach that prioritizes functional performance over flashy aesthetics.
FAQ
How reliable is the 2005 Subaru WRX STI Spec C?
The 2005 STI Spec C is generally reliable when properly maintained. Regular oil changes every 3,000-4,000 miles are crucial due to the EJ207 engine‘s turbo nature. Most examples can exceed 150,000 miles without major issues if maintenance schedules are followed and the car hasn’t been subjected to abusive driving or poor modifications.
What are the common issues with the 2005 STI Spec C?
Common problems include ringland failure (especially when improperly tuned), piston rod bearing wear, turbo failure after 60,000-80,000 miles, and head gasket issues (though less common than non-STI models). The carbon buildup in the intake valves and valve cover gasket leaks are also relatively frequent maintenance items as these cars age.
What’s the tuning potential of the Spec C model?
The Spec C’s EJ207 engine responds exceptionally well to tuning. With basic bolt-on modifications and professional tuning, power can safely increase to 330-350hp. With upgraded internals, turbo, and supporting fuel system, 400-500hp is achievable while maintaining reasonable reliability. The Spec C’s stronger internals from the factory provide a better baseline than standard WRX models.
What are the best first modifications for a Spec C?
The most effective initial modifications include a cat-back exhaust system, cold air intake, and a proper ECU tune to optimize these changes. Following these, an upgraded intercooler, turbo-back exhaust, and boost controller offer substantial performance gains. Always guarantee proper tuning accompanies any performance modifications.
How does the Spec C differ from the standard STI?
The Spec C (Competition) features numerous weight-reduction measures (thinner glass, lighter roof, aluminum hood), a water-spray intercooler system, more aggressive ECU mapping, a mechanical rear limited-slip differential, and specialized suspension tuning. These race-oriented modifications make it approximately 70kg lighter than the standard STI and provide sharper handling characteristics.
What’s the ownership experience like for a Spec C?
Ownership demands commitment to maintenance and proper care. The driving experience is exceptional with razor-sharp handling, immediate throttle response, and impressive power delivery. Fuel economy is poor (typically 16-20 MPG), parts can be expensive, and the ride is particularly firm. However, enthusiasts find these compromises worthwhile for the car’s performance pedigree and increasingly collectible status.
Is the 2005 Spec C legal in the United States?
The 2005 Spec C was never officially imported to the United States market. Examples now appearing in the US have typically been imported under the 25-year import rule or through specialized importers with extensive modifications to meet federal regulations. Potential buyers should thoroughly verify legal status and importation documentation before purchase.
Conclusion
The 2005 Subaru WRX STI Spec C stands as a representation of an era when rally-bred performance and engineering purity reigned supreme. Its relevance today stems not merely from nostalgia but from its portrayal of automotive virtues increasingly rare in modern vehicles: mechanical simplicity, driver engagement, and purposeful design uncorrupted by excessive technology.
As modern cars grow heavier and more digitally insulated from the driving experience, the Spec C’s raw, analog character becomes more coveted. Its lightweight philosophy, communicative chassis, and turbocharged boxer engine deliver sensations that contemporary vehicles—even high-performance ones—struggle to replicate.
In JDM culture, the Spec C represents the pinnacle of Japan’s golden era of performance cars, embodying the philosophy of kaizen (continuous improvement) that Subaru engineers relentlessly applied to the WRX platform. For enthusiasts, owning a Spec C isn’t merely possessing a vehicle; it’s preserving a cultural artifact that tells the story of Japan’s automotive ingenuity and motorsport heritage.
As these vehicles become increasingly rare and appreciated, the Spec C transcends its role as transportation to become an investment-grade collector piece that continues to influence automotive design and inspire passionate drivers worldwide—a true JDM icon whose legacy only grows stronger with time.