Subaru WRX / STI Aluminium Header Tank | Coolant Reservoir (02–07 WRX, 04–14 STI)

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Subaru WRX / STI aluminium header tank manufactured in the UK by The Alloy Shed. Designed as a direct-fit replacement for 2002–2007 WRX and 2004–2014 STI models, this TIG-welded aluminium unit replaces the factory plastic coolant header tank known for cracking and heat fatigue over time.

Engineered for reliability in both fast road and motorsport applications, this aluminium header tank provides a durable upgrade over the OEM plastic coolant reservoir. Suitable for EJ20 and EJ25 turbocharged Subaru engines.

Often referred to as an expansion tank or coolant reservoir, this pressurised Subaru header tank sits at the highest point of the cooling system and functions as the primary fill and air-bleed point.

Vehicle compatibility

Subaru WRX 2002–2007

Subaru STI 2004–2014

Key features

2 mm aluminium construction for strength and heat resistance

WRX-specific laser-cut aluminium mounting bracket for accurate OEM-style fitment

Fully TIG-welded construction throughout

2 × 13 mm swaged hose ports, formed using aerospace-grade beading tooling

1 × 8 mm auxiliary port, swaged for clean, secure, leak-free hose connections

Suitable for road and track use and engine bay upgrades where reliability, fitment and durability matter.

Built properly. Not quickly.