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The GDB dream

If you’re anything like me, your mind will be constantly awash with automotive possibility. Despite having a reasonably sized garage filled with cars in various states of disrepair, I’m forever thinking about ways I can build my dream collection.

Deep down I’ve always wanted to own an Impreza, or more specifically – a WRX that’s had the Subaru Tecnica International (STI) wand waved over it at Fuji Heavy Industries. I’m not exactly sure where the attraction came from, but I’m pretty sure it had something to do with spending one epic week every year from the mid-’90s to the early ’00s, watching Prodrive-built Subaru World Rally Team machines carving up some of the finest gravel back-roads New Zealand has to offer.

So even though there’s no WR (World Rally) Blue STI consuming a spot in my garage right now, if there were I know exactly how I’d want to build it. I could spell out some of those finer details for you, but I thought it would be better idea to just show you. Because Arjun Singh’s super-clean and crazy-quick 2002 GDB Version 8 Impreza is every bit the car I want to own, and more.

Before I start talking about what makes this largely stock-looking STI so special, we need to rewind back to a time before Arjun’s name was ownership papers. He’s responsible for putting some of the finishing touches on the car, but doesn’t take the credit for the work put into the Impreza by its previous two owners.

Arriving in New Zealand barely one-year-old from Japan and with only 10,000 kilometres on the clock, the Subaru’s first Kiwi owner set the car up as a weekend track toy, with a mild upgrade to the suspension and brakes and a set of RAYS Volk Racing RE30 forged wheels with sticky tyres. Somewhere along the line the engine was overhauled too, but when that eventually expired he called time. Enter Gary Capper of Gary Capper Performance (GCP) – a subsidiary of one of Australasia’s most well known and respected Subaru rally car builders – and the company responsible for picking up the pieces and creating arguably one of the toughest WRX street cars in the country.

In modifying the Impreza, Gary made good use of the resources and international championship-winning experience that was available to him in-house at Possum Bourne Motorsport (PBMS). The result: a GDB STI set up to perform like a tarmac rally machine, coupled with the power train of a serious circuit race car; for the street. Not that you’d ever really pick it from the outside.

That was the whole idea of course – enough custom enhancements to separate the Impreza from a standard GDB STI, but not at the expense of its overall factory appearance. Those of you with an eye for detail might have already picked up on the Aeroquip flush-fitting bonnet latches, the air intakes in the front bumper and these very cool rally-spec door mirrors. Like the intakes, the mirror housings were custom made in PBMS’s specialised composites department from full carbon fibre.

As subtle as those tweaks are, the same can’t be said for the wheels. The car came to Arjun on the aforementioned RE30s, but to change up its look, they were quickly swapped for a set of Work Emotion XD-9s in a wider 18×9-inch fitment. The most aggressive set of wheels to grace all four corner however, are the latest additions – polished three-piece Work Meister S1s, with staunch 18×9.5-inch +24 proportions.

They might be barely contained by STI’s factory fattened guards – something I assume might soon be remedied by some careful refashioning of the arches – but I definitely get where Arjun is going. In my rear view mirror on the way to our first location, it looked angry.

Apart from those personalisations though, the Impreza largely looks the way STI intended it to. In many ways it’s the perfect juxtaposition to what lies within.

Why? Because as much as I love the way the GDB’s exterior has been respected, it’s what lurks under the lightweight aluminium STI bonnet that really defines this car. Six hundred plus horsepower worth of hard-tuned Subaru boxer four…

Big boxer tricks

The aforementioned engine blow that prompted the original owner to part ways the car and Gary to purchase it, was also the catalyst for a serious build that’s done away with the broken factory 2.0L block in favour of a 2.5L closed deck equivalent. For strength’s sake, the EJ25 base has been upgraded with custom steel liners, CP forged pistons and Argo connecting rods.

Not that you get much of a glimpse of them under all that polished metal, but the GDB’s original Version 8 cylinder heads were retained, albeit ported for improved flow before being bolted to the prepped block with beefy studs.

And then there’s the turbocharger. From the outside it might look like the 600hp-capable Garrett GT3582 that was originally fitted to the engine during its second build, but on the inside it’s a completely different story. Arjun had local turbo specialist Motorsport Engineering give the big single a performance rebuild with one of its Holset-based HRC40RS cores. Along with more potential, improved response and increased torque is the result. There’s a one-off PBMS/GCP unequal-length steam pipe exhaust manifold in the mix too, along with a TiAL 44mm wastegate for boost controller and a large front-mount intercooler with custom PBMS/GCP pipe work.

Taking its cues from a Group A STI/Prodrive WRC engine, the reversed intake manifold with its large plenum and tuned-length runners for improved air flow and increased power is another hand-formed PBMS/GCP creation. Same goes for the 3.5-inch down pipe and 3-inch stainless steel exhaust system.

There’s a demand for a lot more fuel of course, and no corners have been cut in that department either. In the factory scenario a single feed provides for both fuel rails, but that was never going to cut with the sort of numbers being chased. Now there are dual feeds from an adjustable regulator with Sard Racing split fuel rails and Injector Dynamics ID2000 injectors supplying the high octane pump gas.

It doesn’t stop there either. Along with a 12-litre STI Spec-C intercooler water spray tank, the boot space is home to a pair of Bosch Motorsport 044 fuel pumps running through a custom PBMS/GCP swirl tank.

The fit out, especially when it comes to the fabricated components, is what sets this build apart for me. But really, I wouldn’t expect any less from a workshop that’s regularly tasked with building low-volume, but higher-performing limited edition Impreza WRXs for Subaru New Zealand, and even prototype competition cars for Subaru Australia.

The built EJ25 was run-in on PBMS’s engine dyno before to being fitted in the car, with subsequent tuning carried out on GCP’s four-wheel drive rolling road. Prior to the turbo upgrade and a switch from the flashed factory ECU to a Link G4 Storm engine management system, a solid 540hp at the wheels on pump E85 was revealed. There’s much more in it now just waiting to exploited – around 600whp on a pump gas tune, and closer to 670whp on E85 the calculated potential.

To cope with the extra power and torque the driveline has been upgraded with a custom single-plate clutch and a modified gearset for the factory six-speed manual box. The front and rear STI limited slip differentials have been given a performance rebuild too and there’s super-strong The Driveshaft Shop billet axles out back. Whether it all can withstand the extra output that will soon be thrown at remains to be seen, but if the rest of the mechanicals are anything to go by, I don’t think Arjun is going to have any problems.

The right stuff

As I mentioned early on, before Arjun or GCP got their hands on the car, the suspension had already been given a mild circuit tune. Unsurprisingly then, it’s all been retained, adding custom-valved Whiteline coilovers and uprated sway bars front and rear, plus modified lower ball joints, an anti-lift kit and urethane bushes throughout. In the brake department, two-piece slotted rotors were swapped in at both ends, and the STI’s factory Brembo callipers were treated to Endless competition pads. Overall, it’s a good set up that I guess you could say strikes a nice balance between the street and the track.

As extensively modified the mechanical underpinnings of the car are, the interior follows the same factory-first approach taken on the outside. With very low mileage on the chassis, the trim is perfect order too, which only made Arjun want to retain it that way even more.

Again, it’s the little details here. As a JDM import, a 180km/h speedo would have been standard fare, but the instrument panel has been changed out for a WRX STI Version 9 one that better represents the abilities of the car.

The row of Defi meters that measure boost pressure and water and oil temperature could have been housed in an off-the-shelf ABS plastic dash or A-pillar pod, but again it’s been given the PBMS custom carbon fibre touch.

So there you have it – a build goes to show that both restraint and excess can successfully co-exist together when they’re gone about in the right way. It would have been easy for GCP to tear out the interior and cage it up with a pair of race seats, and deal to the outside with an oversized GT wing and aftermarket FRP bumpers and side skirts. But I’m glad that never happened.

I’m pretty sure Arjun’s of the same mind too.

Despite some aspects of this build remaining understated while others are completely overstated, through some careful planning and perfect execution, a really nice balance as been struck here. To me, the only thing better would be if it was living in my garage…

Brad Lord

brad@speedhunters.com