Not Your Average Hot Hatch
This hot hatch may look like a Toyota GR Corolla at first glance, but there’s far more going on under the skin. John Proulx (@1lowrx on Instagram) owns this 2009 Subaru WRX STI, and it hides a power unit almost no one would expect: a 1GZ-FE V12 from a second-generation Toyota Century.
That engine alone would be outrageous in an STI. Still, Proulx pushed things even further by adding a pair of G30-770 turbos, bringing output to a claimed 1,000 horsepower – roughly 700 hp more than the stock Century, a car originally built for quiet chauffeur duties before its ultra-luxury ambitions, not big-boost mayhem. To withstand the extra power, the V12 was fitted with upgraded internals, including forged rods, pistons, and valve springs.
The Drivetrain Plot Twist
The changes didn’t stop at the engine bay, which used to house an EJ flat-four engine. The twin-turbo V12 is paired with a BMW dual-clutch transmission (DCT) sourced from a 2009 335i, connected using a custom-built adapter plate. The build also features a custom intercooler, oil cooler, intake manifold, and exhaust system, all of which help support the substantial performance increase.
Subaru’s signature all-wheel-drive system is long gone. In its place is a rear-wheel-drive (RWD) conversion using a custom driveshaft and a Ford 8.8-inch rear end, the same differential family found in Mustangs and F-150s. Power goes to Weld Racing S71 wheels wrapped in Mickey Thompson drag radials, with the chassis riding on Cygnus Performance coilovers.
And despite adding eight extra cylinders, two turbos, and a completely different drivetrain, Proulx says the car’s weight distribution remains close to stock. Corner-weight readings show it still sits around 59/41 (front/rear), likely achieved through careful component relocation and the additional rear mass provided by the custom axle setup.
Modding Without Restraint
With Subaru suggesting that any future STI halo model is likely to be fully electric, builds like this offer an interesting contrast for enthusiasts. The brand did preview both gasoline and EV concepts at this year’s Japan Mobility Show, suggesting it hasn’t finalized its direction yet.
Regardless of what the future holds, projects like Proulx’s V12-swapped STI show that interest in traditional gas-powered performance remains strong. The owner also has other cars in his household, including a twin-turbo Coyote V8-swapped Forester with a Mustang badge and, fittingly, a Toyota GR Corolla – the very car this STI could be mistaken for.
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