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423BHP GR Yaris Build – Forged, Boosted and Built by Whifbitz

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We’ve just completed our latest GR Yaris build here at Whifbitz, and this one’s a serious step up from stock. Taking the car from a healthy 300BHP to a dyno-proven 423BHP on pump fuel, this Yaris is now forged, boosted, and ready to dominate the road or track.

Engine Internals – Built for Power & Reliability

To ensure this Yaris could handle big boost reliably, we fitted:

  • CP forged pistons
  • Nitto conrods
  • HKS head gasket
  • DP head studs
  • Closed deck block conversion
  • Kelford 267A cams & valve springs
  • Lamspeed Racing baffled sump

Together, this setup strengthens the engine from top to bottom, making it more than capable of handling serious power and high RPM use.

Turbo & Induction Upgrades

Power comes from an Artec Sport 400 turbo, paired with an Eventuri carbon intake kit for maximum flow and responsiveness. This is the first time we’ve fitted the Artec unit, and we’re seriously impressed — lightning-fast spool, zero low-end lag, and an incredible turbo soundtrack that turns heads.

Engine Management

While we could have gone down the EcuTek route, the customer opted for the Syvecs ECU for its added safety features and tuning flexibility — a smart choice for a fully forged build.

Exhaust & Fueling

We installed our Whifbitz big bore race pipe, which removes the cat and GPF, matched to the existing Miltek resonated exhaust system. It now sounds aggressive without being overly loud — just the right tone for the street.

For fueling, we used DeatschWerks 1100cc injectors to support the additional power demands and leave room for more in the future.

Transmission Upgrades

To handle the extra torque, the car now runs an Xtreme Performance Heavy Duty Organic Clutch paired with a lightweight flywheel, offering strength with a factory-like pedal feel.

Dyno Results

On 99RON pump fuel and 1.9 bar of boost, the car made an impressive 423BHP on our dyno. The power curve is smooth and responsive with strong torque from low down all the way to redline.

There’s still more to come with this setup — a touch more boost or an E85 tune would easily push power even higher.

Turbo Soundtrack to Match

Beyond the numbers, this GR Yaris sounds incredible. The Artec turbo delivers amazing spool, wastegate flutter, and that signature whoosh that lets everyone know this is far from stock.

Want a GR Yaris Like This?

If you want your GR Yaris, Supra, or any other performance car built to this level — forged, tuned, and track-capable — get in touch with Whifbitz today.

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