Update 1/18/2019: Jason Fenske of put together a video dissecting all of the upgrades Subaru made to the powertrain, which we've added to this post. Our original article on the S209's reveal, published January 14th, 2019, can be seen below.
In the 15 years it's been available in the US, the Subaru WRX STI has only seen horsepower rise from 300 to 310. Back in 2004, 300 horsepower in a small, all-wheel drive sedan was a big deal, but now? Less so, which is why people have been asking for an STI with more power for years. Finally, Subaru has delivered.
At the Detroit Auto Show, Subaru is showing off the 2020 WRX STI S209, which serves up 341 horsepower from its 2.5-liter flat-four. Yes, Subie bros, the S209 proves that there's still life in the old EJ25. That power increase comes from a new HKS turbocharger with a larger turbine and compressor than the standard STI's turbo, and increased boost pressure. The engine gets forged pistons and connecting rods for extra strength, and to help create a lighter rotating assembly.
Subaru also upgraded the EJ with a new intake system, a new fuel pump, and new injectors. Like the first STI to come to the US, the S209 gets a driver-controlled water spray system to help keep the intercooler, uh, cool. It's activated by a paddle on the back of the steering wheel. The drive modes and center differential have been reworked, but as ever, the only transmission option is a six-speed manual.
The engineers at STI didn't stop at the engine, though. The S209 is 1.7 inches wider than the regular STI with a 0.6-inch increase in track width. That's allowed for 265-section tires in place of the standard 245s. Those tires are Dunlop GT600As bespoke to this car, and the wheels are 19x9-inch forged BBS alloys, naturally painted gold.
The S209 gets new Bilstein shocks, stiffer springs a thicker rear sway-bar, and extra braces and drawer stiffeners for the front crossmember and rear subframe. There's a flexible strut-tower brace, which consists of two steel rods connected in the middle by a bush ball joint. The idea here is that this bar helps stiffen the car laterally, reducing body roll, while allowing for a little bit of longitudinal flex to aid better ride quality.
All told, this new hardware helps the S209 pull 1.0g of lateral grip on the skid pad.
The brakes are new, too, consisting of cross-drilled steel rotors with six-piston calipers up front and two-pistons in the rear, all of which comes from Brembo.
In addition to these measures taken to improve mechanical grip, Subaru worked on upping aero grip. Of course, there's the big carbon fiber wing bolted to the trunk, but there are also dive planes and vents on the front and rear fenders. The roof is made from carbon fiber, which should help lower weight and center of gravity.
This car receives much of its modifications by STI itself after it leaves the assembly line, which means production will be limited. Just 200 units, all earmarked for the US, in fact. The only colors available are the Crystal White Pearl with gold wheels you see here, and WR Blue Mica, which is inexplicably only offered with gray wheels. Seems like a massive oversight, Subaru.
Subaru hasn't announced pricing yet, but expect it to be quite a bit more expensive than the $50,000 Type RA that came out last year. All these changes are significant, though, so the S209 might be worth whatever Subaru charges for it.