Subaru Tecnica International (STI), a wholly owned subsidiary of Subaru Corporation, has introduced the limited edition STI S209, the first-ever S-line STI product produced exclusively for the U.S. market.

As an S-line product, the STI S209 encompasses upgrades in power, handling, aerodynamics and driver engagement, and undergoes final assembly in Kiryu, Japan, where it receives engine modifications and bodywork alterations that in total require it to be homologated for the U.S.A by STI.

The S209 is thus considered the first 'STI-built' Subaru sold in the U.S.A.

Designed with a focus on high-performance driving, the S209 wears an expanded wide-body exterior treatment, which extends the vehicle's overall width to 183.8cm, or 4.3cm wider than a standard WRX STI. The bulging fenders accommodate wider front and rear tracks and 265/35 Dunlop SP Sport Maxx GT600A summer-only tyres wrapped around lightweight 19-inch forged BBS alloy wheels.

The all new tyres are developed exclusively for the S209 by Dunlop, and are a significant contributor to the car's tenacious maximum lateral grip of over 1.0g. Vents on the front fenders provide additional engine cooling, while vents on the rear fenders rectify air turbulence to reduce drag and increase downforce.

Brembo brakes, with cross-drilled steel rotors and six-piston monoblock front calipers and two-piston monoblock rear calipers, provide stout stopping force, thanks in part to upgraded high-friction pads that deliver improved fade-resistance.

Underneath the S209's broader body are specially developed Bilstein dampers, stiffened coil springs, a 20mm rear stabiliser bar and pillow-type bushings for the front and rear lateral links.

The S209 incorporates reinforcements to the front crossmember and rear subframes and a flexible front-strut tower bar and flexible front and rear draw stiffeners. The flexible tower bar, unlike a conventional rigid bar, is split and joined with a pillow ball joint in the centre to be longitudinally mobile while helping laterally stiffen the body of the car. The result is optimum tyre grip during lateral moments combined with compliant ride during longitudinal moments.

Meanwhile, the draw stiffeners apply tension between the body and cross member to optimise chassis flex, improving stability when cornering and delivering better ride, handling and steering response.

A reworked version of the legendary EJ25 2.5-litre turbocharged boxer engine propels the S209. Featuring an STI turbocharger manufactured by HKS, the EJ25 serves up 336bhp at 6,400rpm, thanks in part to a larger turbine and compressor.

The enhanced boxer engine also receives a notable bump in midrange torque, to 447Nm at 3,600rpm, delivering higher corner exit speeds when driving on track.

For ultimate driver engagement, the S209 comes exclusively with a close-ratio six-speed manual transmission that routes power to a full-time Subaru Symmetrical All-Wheel Drive system with front and rear limited-slip differentials, a Driver Controlled Centre Differential, Active Torque Vectoring and Multi-Mode Vehicle Dynamics Control.

The S209 receives multiple tweaks to elevate it from other STI sedans. An STI badge replaces the traditional Subaru star cluster on the centre of the D-shape steering wheel, which is wrapped in Ultrasuede with silver stitching.

An S209 serial number badge resides on the centre console, and S209 badges adorn the passenger-side dash and the headrests of the Recaro front bucket seats, which feature new silver-hued inserts. Outside, special S209 badges are affixed to the front grille and fenders as well as the rear decklid.

Only 209 units of the STI S209 will be built, earmarked exclusively for the U.S. Available exterior colour and BBS wheel combinations will be WR Blue Pearl with grey wheels and Crystal White Pearl with gold wheels. Pricing will be announced closer to the on-sale date in late 2019.