Subaru WRX S4 STI Sport # is a sharper, limited-edition WRX for Japan only

Depending on your nationality, age, and interests, the first association for the # symbol could be pound — for weight or the telephone, number, plain old hash or hashtag, or sharp for the musically inclined. Subaru Japan intends that last meaning for its new WRX S4 STI Sport #, because this is a sharper version of the mass-produced WRX S4 STI Sport introduced to the top of the range last year.

Of note, this vehicle is a standard WRX, not a full-beans WRX STI. The differentiator is the “STI Sport” designation, which has also been applied to the Japan-market Levorg and BRZ, representing a model developed with input from Subaru Tecnica International. Last year’s flagship trim picked up STI-tuned Bilstein DTMatic II inverted struts at front, STI-tuned conventional springs and dampers in back, 18-inch black wheels to go with black trim pieces like mirror caps and decklid spoiler, and a special interior with Bordeaux leather and ultra suede. Output from the 2.0-liter four-cylinder Boxer motor was left unchanged from the WRX S4 at 296 horsepower and 295 pound-feet of torque, shifting through the automaker’s Sport Lineartonic CVT. The sedan costs 4,093,200 yen ($38,050 U.S.).

The limited-edition WRX S4 STI Sport # displays a keener edge thanks to three STI components tested on the division’s Nurburgring race cars — a flexible front tower bar, and flexible draw stiffeners for front and rear. All three components have been available on the aftermarket for a while, but their stock fitment is apparently new. The flexible tower bar looks like a typical strut tower reinforcement, but a pillow ball joint in its middle provides vertical elasticity. The bar maintains rigidity across the vehicle, but when the suspension needs a little give to work up and down, the pillow ball joint allows that. The flexible draw stiffeners are adjustable rods that connect a longitudinal frame member to a component on the cross-member, increasing chassis stiffness. STI says the three parts deliver faster steering response, reduced roll speed, and improved wheel tracking in the case of road ruts or crosswinds without compromising suspension suppleness.

The Boxer sees some tweaks like a freer-breathing air filter and exhaust that raise torque by up to 10%, and sharpen throttle response. Thicker sound insulation in the floor and extra vibration-damping material in the spare tire well cut road noise for all occupants.

If the standard equipment wasn’t enough, buyers could add side and rear under-spoilers to work with the front underside spoiler rectifying airflow to decrease lift. We write that in the past tense because Subaru limited the WRX S4 STI Sport # to 500 units priced at 4,741,000 yen ($44,082 U.S.), all of which sold out in two weeks.  

Some have taken this limited edition as harbinger for what Subaru plans for the coming WRX and WRX STI: namely, more performance, comfort, and a quieter cabin. The CVT-only powertrain will probably — hopefully — continue to be limited to the WRX Premium and Limited. The automaker told TorqueNews that roughly 90% of U.S. WRX STI buyers go for the six-speed ‘box. That leaves the WRX STI out of the company’s EyeSight driver assistance tech, which only works with Subaru’s CVT, and we still don’t know if Subaru will prioritize ultimate safety throughout the lineup or give enthusiasts the transmission they clearly want when the next-gen WRX STI shows up next October or thereabouts.