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Prowear NZ Superlap Series Spotlight: Pro Street GC8 weapon

3 June 2016

We initially spotted Michael Sorenson’s 1998 Subaru WRX STI at the first round of the Prowear NZ Superlap series. What was instantly evident was just how immaculately presented the WRX was, but we only saw the half it.

Little did we know that lying beneath the gloss-white bonnet was an angry — and no longer factory — boxer engine that puts out 394kW (528hp) at the wheels on high boost. Michael did like the idea of building a race car from scratch, but he initially thought it would be more economical to purchase something already built, or close to it.

After trawling the internet a couple of years ago, a bargain was found on one of New Zealand’s largest Subaru-specific forums, Clubsub. However, what they say about projects when they’re 90-per-cent complete is that there is 90 per cent of the work left to do, and this rang true for Michael and the Subaru.

Components that weren’t installed correctly were replaced, and the motor was finished with a final tune with E85 fuel, to keep engine temp down and give more power. The Subaru, now complete, proved extremely fast at its first Superlap series, but Michael tells us he is focussing more on his driving first.

The boost has been turned down whilst he learns, but come next season the wick will be turned up, and Michael will put the full 400kW of fury to the tarmac.

1998 Subaru WRX STI (GC8)


  • Model: EJ20T, 2000cc, four-cylinder
  • Block: Closed-deck block bored to 2350cc, forged 97mm pistons, 2500cc crank, Killer B baffled sump
  • Head: V5 STI heads, 280-degree Kelford cams, adjustable cam gears
  • Intake: Custom intake piping by Sinco Customs, front-facing intake manifold
  • Turbo: Garrett GT3082R (with anti-surge cover), Sinco Customs tuned-length headers
  • Wastegate: 44mm TiAL 
  • BOV: Turbosmart Supersonic
  • Fuel: Intank Walbro fuel pump, Dytech Racing surge tank, twin external Walbro fuel pumps, Teflon fuel lines, SX Performance fuel filter, SX Performance fuel-pressure regulator, custom fuel rails, Injector Dynamics ID2000 injectors
  • Ignition: Factory
  • Exhaust: Straight-through exhaust system
  • Cooling: Twin 12-inch fans, alloy radiator, custom Sinco intercooler piping, front-mounted intercooler
  • ECU: Link G4 plug-in 


  • Gearbox: WRX STI V8 six-speed 
  • Clutch: Heavy-duty Exedy 
  • Flywheel: Factory
  • Diff: WRX STI V8
  • Support
  • Struts: Cusco coilovers
  • Brakes: WRX STI V8 Brembo calipers, slotted and drilled rotors, Mintex 1166 pads, stainless steel brake lines
  • Other: Whiteline front and rear sway bars, Whiteline front and rear strut braces, Cusco rear stabilizer bar, Whiteline sway-bar links and mounts


  • Wheels: 17×8-inch Work Emotion 
  • Tyres: 215/45R17 Toyo R888
  • Other: 30mm Torq spacers


  • Paint: White respray
  • Enhancements: V5 STI body kit, Chargespeed bonnet vent, Cusco rear wing, RA wing mirrors


  • Seats: Racetech 4009HR, Sabelt six-point harness
  • Steering wheel: Sportline Imola suede 
  • Instrumentation: Gizzmo shift light, Prosport Evo gauges
  • Other: Window net, roll cage


  • Power: 394kW at the wheels 

Driver profile

  • Driver/owner: Michael Sorenson 
  • Age: 30
  • Location: Auckland
  • Build time: It’s a work in progress
  • Length of ownership: 2.5 years
  • Thanks: E&H Motors, Fraser Cars, and Chloé for putting up with the track days

This article was originally published in NZ Performance Car Issue No. 231. You can pick up a print copy or a digital copy of the magazine below: