Documentary photographPhoto: Tokumeigakarinoaoshima · CC0 1.0 · resized and cropped · Registration identifier pixelated for privacy.
Engine redprint / verifiedEJ20 2.0 L twin-scroll turbo flat-four
2.0 L flat-4 · turbocharged · EJ20 2.0 L twin-scroll turbo flat-fourLongitudinal front engine, symmetrical all-wheel driveTopology diagram · not to scale · based on the cited primary sources
The GRB moved Subaru’s flagship Impreza performance model into a wide-body five-door format while retaining the Japanese EJ20 and six-speed all-wheel-drive system.
R / production rarity
How rare is it?
A simple 1–5 rating based on completed worldwide production for this exact version. Price and desirability are not included.
Rarity ratingNot availableNo comparable worldwide production total
Production bandNot available
Production evidenceNo exact production total
ProducedWorldwide total used for the rating
Production total unavailable
A reliable worldwide figure is not listed in the references.
How the rating works
The rating uses five fixed production bands. Smaller production runs receive higher ratings. Exact totals and responsibly sourced estimates for this precise version can be rated. Plans, regional totals, lower bounds, disputed figures and broader-family totals remain visible but unclassified. The evidence description is kept separate from the rating so a source limitation cannot change how scarcity is measured.
Subaru built the Impreza WRX STI (GRB) from 2007. The GRB moved Subaru’s flagship Impreza performance model into a wide-body five-door format while retaining the Japanese EJ20 and six-speed all-wheel-drive system. Its five-door performance hatchback form and turbocharged all-wheel-drive performance hatchback purpose locate it within a specific chapter of the marque’s performance history.
The focus here is the October 2007 Japan-market CBA-GRB Impreza WRX STI five-door with 2.0-litre EJ20 and 308 PS, excluding 2.5-litre export cars, later saloons, Spec C and named editions. That scope is important: familiar badges can cover several engines, markets and model years, while road cars and competition derivatives may share a name without sharing a usable technical specification.
The mechanical centre is the EJ20 2.0 L twin-scroll turbo flat-four, a 1,994 cc turbocharged flat-4. The period specification represented here is 227 kW (308 PS) and 422 Nm. Those figures stay attached to this configuration rather than blending regional tunes or later revisions.
The Japanese launch GRB combined a twin-scroll EJ20, six-speed manual, multi-mode DCCD and a new five-door platform The installation is longitudinal front engine, symmetrical all-wheel drive, working through a 6-speed manual with driver-controlled centre differential. That combination determines throttle response, traction and the path by which induction, combustion and transmission sound reach the cabin and roadside.
Engineering and character
Useful listening markers include twin-scroll turbo EJ20 flat-four, high-rpm turbo response, six-speed manual shifts, DCCD all-wheel-drive transmission note. A genuine cold start records cranking, first combustion and the transition to a settled idle; a warm restart is a different event and should be labelled as such.
Under acceleration, microphone position and engine load reveal different layers. An engine-bay or cabin recording can expose induction and valvetrain detail, while an exterior pass gives more weight to exhaust, tyres, turbocharger or supercharger behaviour and the acoustic effect of speed.
The GRB identity also makes comparisons within the Impreza family meaningful. Closely related editions may differ in intake hardware, boost control, gearing, catalysts, silencers or mass, so their recordings should not be treated as interchangeable merely because the body shell looks similar.
Surviving examples frequently carry replacement exhausts, wheels, suspension or engine parts. Those cars can still make valuable contributions when the changes are documented; the archive simply needs to distinguish a modified survivor from an evidenced factory-stock reference.
Legacy and identity
The 2007 production period supplies another boundary for research. Manufacturers revised emissions calibrations, equipment and market availability during model runs, and historic output may appear in PS, kilowatts or regional horsepower standards. Keeping units and market context visible prevents false precision.
Body layout matters to sound as much as specification sheets suggest. The five-door performance hatchback changes cabin volume, resonance and the listener’s distance from the powertrain. Engine position, driveline and body openings can therefore make related engines feel substantially different in use.
Period photographs establish design and historical context, but appearance alone cannot prove untouched mechanical condition. Originality should be described component by component, especially for intake, forced induction, catalysts, silencers, transmission and final-drive hardware that can alter performance and sound. Service records and dated photographs can make those distinctions clearer without asking readers to accept appearance as proof.
The Impreza WRX STI is therefore best understood as a connected mechanical identity: EJ20 2.0 L twin-scroll turbo flat-four, 6-speed manual with driver-controlled centre differential, all-wheel drive and the GRB boundary. Preserving those elements gives readers a useful story now and gives future community recordings an exact historical home.
01
Model identity
The focus here is the October 2007 Japan-market CBA-GRB Impreza WRX STI five-door with 2.0-litre EJ20 and 308 PS, excluding 2.5-litre export cars, later saloons, Spec C and named editions.
02
Why it matters
The GRB moved Subaru’s flagship Impreza performance model into a wide-body five-door format while retaining the Japanese EJ20 and six-speed all-wheel-drive system.
