Most people aren’t game enough to drop stacks on a practically brand new car and go about modifying it straight away, but, for Seng Tran and his 2015 Subaru WRX STi, that’s exactly what happened. He explains: “It started out as a New Zealand–new 2.5-litre EJ25 car. With bolt-ons and a Tomei M8265 it made 432hp [322kW] at the fly on around 22psi. The initial intention was to thrash it until the EJ couldn’t take it anymore, and eventually it did fail.”
That failure proposed an ultimatum: either sink in a built example of the EJ25 and see what can be squeezed out of it, or increase the cylinder count by two and make some serious grunt — you can probably already guess which one Seng went for. The EZ30 chosen for the task bumps capacity up to three litres, having originally been found within the Subaru Legacy–model family, and has been proven to be good for wild amounts of power without having to lean on it stupidly hard like its predecessors.
Possum Bourne Motorsport (PBMS) was charged with the conversion and sunk a dummy motor in place so that Sinco could fabricate the required components to accept boost via a side-mounted BorgWarner EFR 8374. The team also whipped up the intake plenum that commands the engine bay, made all the pipework and exhaust, and relocated the battery.
Once all the fabrication has been taken care of, the STi is set to go back to PBMS for the motor to be built the monster required to generate the 500kW power goal. It will see Supertech forged pistons and rods crammed inside the closed-deck block, with PBMS modifying the oil galleries; porting and polishing the heads; and adding bigger fuel injectors, an upgraded drive-by-wire throttle body, and V7 STi coils.
“After it’s all finished, it will be my daily-driver,” Seng tells us. “And [will see] the occasional track day.”
Five hundred kilowatts at the depression of the loud pedal on the daily isn’t something to scoff at, and it won’t be subtle in the aesthetics department either. Seng has draped the exterior in carbon-fibre and wide-body goodies, opting to run a full HT Auto bodykit with HT Auto wide-body fender flares, an APR Performance carbon-fibre front splitter, Carbon Reproductions replacement mirrors, and APR carbon-fibre canards, all wrapped in bronze — it will sit over 18x10.5-inch Enkei RPF1s at all corners as pictured.
You’ll hear it before you see it, and once your eyes are locked, it’ll be hard to pull them off of this GT-styled street-brawler.