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Boxer Punch

The owner of this modified STi was addicted to Subaru boxer power from his first moment in the passenger seat!

Words by Michael Knowling, Pix by Julian Edgar

Click on pics to view larger images

At a glance...

  • MY03 face-lift STi
  • Bolt-on upgrades
  • HKS extractors
  • 240kW ATW with total reliability
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If you ever needed proof that the Subaru WRX and STi have changed the face of performance motoring forever, well, here it is.

Tristan of Sydney previously owned a Mitsubishi Lancer, Jeep Cherokee and Alfa 33 but when he went for a ride in a mate’s WRX in 2001, it left a lasting impression.

"I couldn’t get over how good it was," says Tristan.

"At that moment, I fell in love with Subarus and told myself I was going to get one," he says.

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After researching everything there is to know about WRXs and STis, Tristan was on the verge of purchasing a brand new STi back in 2002. However, at the last minute he pulled the plug and decided to wait for the face-lifted (and much more attractive) model which appeared in early 2003.

And that’s when Tristan joined the ranks of Subie owners.

"I was very impressed by the standard car," says Tristan.

"The acceleration and handling were just fantastic for a mass-produced sedan," he says.

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But, as many WRX/STi owners can attest, once you get caught up in the whole STi ownership thing it’s difficult to avoid splurging on a couple of aftermarket tweaks. Tristan’s first was an MRT 3-inch mandrel bent exhaust fitted in conjunction with an EcuTeK custom tune.

These two simple mods gave dramatically improved drivability and around 160kW+ at all fours.

"Its performance was just fantastic out in the country," says Tristan.

But with various aftermarket companies promoting some truly spectacular Subaru upgrades, it was impossible to stop at that...

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Next, the standard turbocharger was replaced with an APS SR40 turbocharger with associated up-pipe. This big huffer inhales through an MRT silicone pipe and in-guard pod filter kit. A big MRT front-mount intercooler kit replaces the stock STi top-mount unit, which suffers heat-soak issues in stop-start driving. A GFB blow-off valve, oil/air separator and high capacity sump are also installed.

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Peak performance is liberated from these mods with a custom ECuTeK remap – and note that the new mapping is MAP sensor based, not airflow meter based. Fuel delivery is enhanced with a set of 800cc replacement injectors, MRT fuel rails and a high-flow pump. The ignition is standard except for 1 range colder iridium spark plugs. Boost pressure is set to a maximum of 23 psi.

Interestingly, Tristan has recently had a set of HKS extractors installed. We’re told that these necessitated a lot of tuning and best results didn’t come until the extractor pipes were heat wrapped. This provides a thermal efficiency boost that gives increased output across the range.

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As you can see, an aluminium coolant radiator has been slotted into the picture for the purpose of improving the under-bonnet appearance. Other under-bonnet eye-candy includes polished intercooler pipes, blue silicone hoses and matching slip-over hose covers. A nice upgrade – nothing over the top.

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Another interesting addition is a FHRX Studios Earthing and Battery upgrade, which gives 5 separate earthing points. Tristan says this eliminated problems with the alarm false-triggering. He explains that the standard (small) battery is prone to voltage fluctuations, which are detected by the alarm system. We’re also told that the earthing and battery upgrade smoothed out the power curve.

So how much power are we talking?

Try 240kW at the wheels on a Dyno Dynamics chassis dyno – almost double the already substantial factory output!

With 28,000km on the odometer, the engine and 6 speed driveline have been utterly problem-free. The standard clutch currently survives – Tristan says he doesn’t torture it with brutal ‘Saturday night special’ launches.

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The handling of an Impreza STi is already pretty special so there hasn’t been any need to go chopping and changing things. The only variation is lowered STi springs, which we’re told were an option when new. The braking system is standard Brembo with DBA 4000 slotted replacement discs.

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Visually, it’s hard to believe the body is all standard - STi certainly held nothing back with the towering rear wing and humungous bonnet scoop! The facelift ’03 nose is also a big improvement over previous models. Tristan has enhanced its appeal with 18 x 8 inch HR Racing alloys clad in 225/40 18 Toyo rubber.

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Inside, it’s a similar story. The STi cabin already brings supportive seats, a sports dash and aluminium good bits. The only subsequent addition is an EcuTeK in-car dash display, which is mounted at the top of the dash where the factory LCD clock usually resides.

Tristan tells us he’s more than happy to keep the car for a few more years and gradually add more and more to it. For example, at the time of writing, a GReddy front bumper lip and some more under-bonnet detailing was about to appear. But more important is the plan to go for one of MRT’s popular 2.5 litre forged piston engines – this and a GT35 turbo should see 300kW at all four wheels!

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But for now, keep an eye out for this car at the Sydney drags – it should run a high 11 second pass in its current configuration before stepping up to the big cube motor.

Yep. It’s safe to say Tristan is yet another Subaru convert!


MRT Performance +61 2 9809 2110

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