A new, more hardcore version has been added to the line-up of the Subaru Impreza WRX STI. On sale today in Japan, the newest member of the Impreza WRX STI family that bears the Spec C moniker will be produced in a limited run of 900 units. The model features an array of improvements including engine and chassis performance upgrades as well as a lighter body. 
Based on the standard Impreza WRX STI, the Spec C is powered by a tweaked version of Subaru's 2.0-liter boxer engine with a remapped ECU and new ball bearings for the turbine axle bearing. The turbocharged four-cylinder unit produces an output of 308 PS at 6,400 rpm and 422 Nm of torque at 4,400 rpm with Subaru promising quicker response and improved accelerating performance over the base model.
To improve the car's handling, Subaru's engineers retuned the front and rear suspensions while they also made changes to the steering system. In addition, the rear LSD (Limited Slip Differential) system has been changed from a Torsen type to a mechanical type. The Spec C rides on newly designed 18-inch wheels shod in 245/40 R18 Bridgestone "POTENZA RE070" tires.
Finally, the adoption of an aluminum engine hood, laminar window glasses and a downsized battery plus the replacement of the spare tire with a repair kit resulted in a lighter body.
Outline of Subaru Impreza WRX STI spec C
Enhancement of Engine performance:
- Ball bearings of the turbine axle were newly adopted to reduce friction in the turbocharger. With the optimized ECU programming, the engine offers smoother and quicker response to the accelerator pedal and excellent accelerating performance.
- An inter-cooler water spray prevents rise in intake-air temperature at continued high-load driving, providing stable engine performance and improved efficiency.
Enhancement of Chassis performance:
- Reinforcement of the cross member in front-suspensions offers a linear steering response.
- Specification changes in damping force of suspensions, coil spring rate, rear stabilizer and rear sub-frame bushes optimize rigidity for body roll and retain excellent road-holding capability.
- Rear LSD (Limited Slip Differential) system was changed to a mechanical type from a Torsen type to obtain the steady and powerful traction during cornering.
- Bridgestone "POTENZA RE070" (245/40R18) were adopted to enhance cornering ability and higher grip performance, especially in dry conditions.
- Nimble handling with a firm steering feel is assured by increasing oil flow volume in the power steering system.
Lightened body:
- An aluminum engine hood and a downsized battery, which make the front section of the vehicle lighter, produce better maneuverability.
- Laminar glasses were adopted in the front and side windows. They lightened the upper section of the body weight, resulting in improved stability during cornering.
- Newly-designed lightweight 18-inches alloy wheels are standard to offer excellent road-hugging property by reducing unsprung weight. (17-inches alloy wheels are optional)
- A flat tire repair kit is standard, which also helps weight reduction.
Others:
- A structural change of fuel pomp provides stable fuel delivery even on high-load driving.
- Gold colored "brembo" brake calipers are standard.
- The front bucket seats (fabric with red stitch) are standard on models with 18-inches alloy wheels.
- The "RECARO" seats (Alcantara and leather combination with red stitch) are optional on models with 18-inches alloy wheels.
- Two exclusive exterior colors are available; Sunrise Yellow and Pure White.
- The production is limited to 900 units.
Major specifications:
- Engine type: Horizontally-Opposed 4-cylinder DOHC 16-valve turbocharged engine
- Displacement: 1,994 cc
- Maximum output: 227kW (308 PS)/6,400 rpm
- Maximum torque: 422 Nm (43.0 kgf·m)/4,400 rpm
- Turbo type: Ball-bearing type twin scroll turbocharger
