SUBARU WRX STI (2005–2007)
Our final contender is something of a left-field choice for this challenge, boasting neither a high top-speed in factory trim, nor sleek aerodynamics. But Subaru’s iconic WRX STI is the most popular Japanese performance car of the JP era. It is also lighter than the other two contenders and much cheaper to buy – leaving a lot of cash in reserve for some major modifications. And with the right approach, the WRX STI can be moulded into a 500bhp+ 200mph monster.
Your best Scooby starting point would be the 2005 to 2007 ‘Hawk Eye’ WRX STI, which boasted a longer wheelbase, sharper steering, a larger-capacity 2.5-litre boxer engine for UK models, and DCCD. Prodrive produced a Performance Pack (PPP), which took a standard STI from 276bhp to 316bhp. More extrovert
STI buyers however choose the Black RB320 limited edition – with the PPP, a bespoke chassis (boasting Bilstein dampers, Eibach springs and a lower ride height), a mesh grille and a new front lip spoiler. Japan also received a Spec C and Spec C Type-ra models, with the ‘WRX’ part of the model’s name dropped, simplifying it to the Subaru Impreza STI.
The 2007 RB320 limited edition (produced in memory of Richard Burns, the 2001 WRC World Champion who had died in 2005) had 332lb ft of torque at 3750rpm, with 60mph smashed in just 4.8 seconds. Production finally ended in 2007 to make way for the all-new third generation 2008 Impreza hatchback.
A decent Hawkeye STI will set you back just £9000, and would be the starting point of choice for Subaru tuning guru Matt Baker, of MB Developments. ‘The benefit of this model is the very strong longer-ratio gearbox, with a taller 5-6th gear ratio that will top out at over 200mph with no modifications needed from the drivetrain,’ Matt explains. ‘This means less stress on the engine and turbo with lower revs needed to hit the magical 200mph figure.’
With a revised front end they have a relatively low 0.33 coefficient of drag from the factory, and this can be improved somewhat. ‘Simply slipstreaming the front-end grille and shut lines wherever possible makes a big difference, as well as deleting the OEM air scoop and wing mirrors.’ Keeping the big rear spoiler would be wise, though, to aid stability.
‘Personally, I'd also be looking at lowering the centre of gravity,’ suggests Matt. ‘It's not a must, but it does reduce the drag and makes the car more stable at the same time.’ Coilovers would be your best option. Turning our attention to the engine, a set of replacement forged pistons and con rods are a must, as well as race type bearings. ‘I’d recommend a set of tried and tested items such as those from ACLOR Cosworth/mahle,’ suggests Matt, ‘Plus a set of uprated 11mm or bigger head studs and multi-layer steel head gaskets.’ A modified oil pump is also a must to keep the motor together under higher levels of stress.
‘Once the engine internals have been addressed you’ll need a larger turbocharger and a front-mount intercooler, as well as a high-flow 320lph fuel pump and matched larger injectors,’ Matt continues. ‘Next up you will need a 3in exhaust system with a sports cat or decat, plus a set of tubular headers like RCM GT Spec 2 items.’ A high-flow induction kit with a good supply of cold air will also be required to feed the larger turbo, along with an oil cooler to keep the oil at a working temperature. ‘The OE water system is very good though, and these rarely need touching,’ Matt adds. And then it’s time for the ECU. ‘This is one of the most vital parts of the build,’ Matt emphasises, ‘So choose your ECU and mapper wisely. We recommend Syvecs ECUS.’
Finally, you should look to shed as much weight from the car as possible, so ditching the heavy airbag equipped front seats and rear seats for lighter items makes sense, as well as removing sound deadening material and unwanted items like tools, the spare wheel/jack and seat-belt brackets – and adding a rollcage. Don’t attempt high speeds without one! High-speed tyres, racing harnesses and a fire extinguisher are also essential. Matt reckons just over 500bhp should see a lightened, lowered, slip-streamed STI capable of 200mph. With an estimated spend of £14,000 on modifications and a
£9000 base car the total expense would be around £23,000 – undercutting both the other contenders.