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STi Sacrilege?

Despite its collector appeal, a 2-door STi should never be retired to the garage - it's supposed to be driven!

By Michael Knowling

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Amid the hoard of WRXs in Australia it takes something significant to stand out from the flock. A barrage of fibreglass body add-ons and a big set of rims simply won't cut it. Sean Day from Adelaide's S&J Automotive has just the vehicle to bring WRX owners to their knees - a 2-door Version 5 STi (one of only 400 imported to Australia).

Sean and his wife - Joanne - make up the S&J component of S&J Automotive. S&J specialise in - surprise, surprise - Subaru enhancement and are the sole MRT distributors in South Australia. Curiously, Sean and Joanne became Subie fans after owing various European and American vehicles - everything from a Cortina GT, to a 635 and 325is BMW and a Ford Mustang! Their first Rex was a MY99 sedan, which went down the 3-inch exhaust, high-flow air intake and UniChip road. Sean says this was a pretty decent all-round car, with more than enough squirt to annihilate any traffic light pretenders. In it's final guise, the '99 Rex made 140kW at the wheels (measured in third gear on a Dyno Dynamics chassis dyno).

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Keen to jump into something "a little bit more special" Sean traded his tweaked WRX on an immaculate 25,000 kilometre Version 5 STi 2-door. Without question, this is the most desirable WRX ever officially imported to Australia - it's the model hard-core WRX fans just can't get enough of. Sean recalls, "Even when it was completely standard, I loved the overall feel of the STi 2-door. It gave that big turbo rush through the top-end, the gear ratios were better stacked and it felt more purposeful on the road. It was fantastic".

"Terrific" still leaves room for improvement though...

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The first stage of development saw the STi breathing easier though a 3-inch mandrel exhaust (using a MRT front pipe, high-flow cat and a Trust centre and rear section), an AVO single entry top-mount intercooler and a Rampod air intake. To maximise the gains from these mods, a Link laptop programmable ECU was installed and tuned by Sean (note that the Link eliminates the need for the factory airflow meter).

So what sort of power increase are we talking here? Well, the STi started off making 144kW at the wheels (on the standard 17 psi boost setting) and it ended up pushing 168kW at the treads with only 1 psi more boost. "That was an excellent set-up," says Sean "and, to be honest, I'd recommend that most people stop there. It was responsive, reliable and much quicker than standard". A 12.7-second quarter mile - with a fairly gentle launch - is hard evidence of that. The only other mod at this time was a super low set of King springs.

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Stage 2 of engine development - which has been only recently completed - involved some more serious bolt-ons; no need to delve inside the engine just yet. First, the stockie VF28 STi turbocharger (which had so far performed admirably) was replaced by an "experimental" TD05/Evo turbocharger with a 20G compressor wheel. Claimed good for around 425 horsepower, this hybrid turbo was designed to minimise spool-up time compared to other aftermarket offerings in a similar power range; after limited testing, Sean says it seems to do the trick. Oh, and - by keeping the (chromed) turbine heat shield - the big turbo conversion is very nicely integrated; most people would completely overlook it.

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The rest of the 'Stage 2' engine mods are relatively minor but, when combined, they make a real difference to throttle response and power. A GFB (Go Fast Bits) pulley kit reduces the parasitic loss caused by the engine accessories, while a GFB atmospherically venting BOV ensures there's no boost leakage and allows the turbo to recover faster after gear changes. To prevent cylinders leaning out under load, Sean has also fitted a fuel rail mod that incorporates an additional fuel pressure reg. Spark energy is maintained by a fatso set of 10mm Top Gun plug leads sprouting from the standard coil pack.

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With a retune of the Link ECU, Sean hit the chassis dyno again to see what sort of improvement this second round of mods gave. As you can see, peak power is now just over the magic 200kW mark - 201.5kW running up to 22 psi boost. Just prior to our photo shoot, however, Sean made the switch to a MRT top-mount intercooler (complete with a silicone feed hose) and commented that the car definitely feels stronger - "I reckon it's got an extra 5 or 10 kilowatts".

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Despite copping the strain of extensive product testing and development, the standard STi driveline held up exceptionally well. It took about 15,000 hard kilometres before the standard clutch started showing signs of slip, "it wasn't slipping badly, it'd just slip a bit if I wasn't off the clutch pedal quick enough between gear changes" explains Sean.

These days, the tuned STi motor is backed by a ceramic button clutch, heavy-duty pressure plate and MRT billet flywheel and the gearbox is nothing less purposeful than an S&J-marketed dog box. This specific gearbox uses dog engagement for 1st to 4th gear, while 5th gear retains the factory helical gear - this keeps cost down and reduces noise while cruising in top gear.

And this isn't the only vehicle owned by Sean and Joanne that's serious enough to require a dog box. The husband and wife team recently got into rallying in a big way, using imported Legacy RS and RS-R turbos as their weapon of choice; Joanne tillers while Sean calls the corners. Over the past two full seasons, Sean and Joanne have made some excellent showings, though their last season was hampered by recurring gearbox problems - an 'unbreakable' dog box arrived, but too late to claw back any ground in the championship.

Anyhow, getting back to the tudor...

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With 40,000 clicks on the odo the standard STi dampers - working with the aforementioned super low springs - apparently felt quite worn. Sean decided to replace all four with a set of KYB AGX adjustable dampers, which keep suspension movements very well controlled. Handling has been further transformed with fitment of a Whiteline 22mm adjustable swaybar with heavy-duty links and a Whiteline anti-lift kit. "Flat" and "balanced" are two of the words Sean used to describe the car's handling. Tucked up under the guards are Version 7 STi rims (17 x 7.5-inch) wearing lo-profile rubber. Peer through the front wheel spokes and you'll see a DBA Kangaroo Paw disc. In conjunction with MRT sports pads the car now stops noticeably better than standard; still, better braking ability never goes astray...

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With a power-to-weight ratio of around 230kW (flywheel) per tonne you don't need any complex formula to decipher this machine is quick - damn quick. We caught up with Sean and the car at a recent Adelaide drag event where a best time of 12.4-seconds was recorded. Sean's quick to point out, however, it was a fairly hot day (we've even got the sunburn to vouch for that!) and he was forced to used less-than-usual boost - about 18 psi. Given the right conditions the car will certainly go quicker.

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So how much further will Sean proceed to chop and change his precious 2-door STi? Time will tell, but there are serious discussions about a 2.2-litre stroker and, just maybe, a pumped set of 22B-style guards. Joanne isn't too keen on that last idea though - as she says, you're not really meant to do stuff like that to a collectable vehicle like this.

I think the agreement is to hold off until they can track down a genuine 22B; and, no, don't expect that to stay standard!

Contact:

S&J Automotive
+61 8 8377 3077

www.sjautomotive.com.au

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