HKS 71008-AF013V for Super SQV 8-22 RETURN KIT GRB/GRF

Vehicle Fitment

• 2008-2014 Subaru Impreza WRX STI Hatchback - GRB platform (EJ207 2.0L turbocharged flat-4, AWD)
• 2009-2014 Subaru Impreza WRX STI 5-Door - GRF platform (EJ257 2.5L turbocharged flat-4, AWD)
• 2011-2014 Subaru Impreza WRX STI Sedan - GVB platform (EJ207 2.0L turbocharged flat-4, AWD)
• 2011-2014 Subaru Impreza WRX STI Sedan - GVF platform (EJ257 2.5L turbocharged flat-4, AWD)
• 2015-2021 Subaru WRX STI Sedan / Hatchback - VAB/VAF platform (EJ207 / EJ257 turbocharged flat-4, AWD)

Fitment Notes

• This is the 71008-AF013V bundle - it includes both the Super SQV4 vehicle-specific kit (71008-AF013) AND the suction return kit (71002-AF002) in one package. The standalone BOV kit without the return kit is sold separately as 71008-AF013
• The suction return kit (71002-AF002) included in this bundle routes blow-off air back into the intake tract (recirculating / recirculation configuration), preserving the factory MAF signal and preventing idle hunting, rich fueling, or stalling that can occur when vented-to-atmosphere BOV air is not returned on a MAF-based engine management system
• Fits both JDM EJ207-powered (GRB, GVB, VAB JDM) and USDM EJ257-powered (GRF, GVF, VAB/VAF US) STI variants - the BOV mounts to the same intercooler outlet pipe location regardless of engine displacement
• Uses the same mounting flanges as all previous generations of HKS Super Sequential Blow Off Valves - compatible with all previous-generation SSQV inserts, recirculation fittings, and optional recirculation kits
• This product is not CARB legal and is not for sale in California

Features

• Sequential valve structure - HKS introduced the original Sequential Blow Off Valve in 1994, pioneering the pull-type sequential design that has since become the industry reference. The SQV4 is the fourth generation of this valve, refining the physical design while preserving the functional architecture that defines the series
• Pull-type relief design - the valve opens by being pulled open via vacuum differential rather than pushed open by boost pressure, providing more precise and consistent opening characteristics across the full boost range without the pressure threshold variations that affect push-type designs
• Differential pressure control system - measures the pressure differential between the intake manifold vacuum and the intercooler pressure to determine valve opening timing and duration, enabling stable and responsive operation from low boost to high boost without requiring separate adjustment for different boost levels
• Broad operating range - the differential pressure control approach allows the SQV4 to function correctly on stock boost pressure as well as on significantly elevated boost levels, making it suitable for both stock and modified STI builds without valve adjustment
• Nickel-plated die-cast metal secondary valve swaged to primary valve - provides improved sealing quality and durability over previous generations; the swaged connection between primary and secondary valve elements ensures structural integrity under sustained high-boost cycling
• Stainless steel C-clip - internal retention component for increased sealing pressure and long-term durability in the valve assembly
• Vehicle-specific pipe and hardware - the 71008-AF013 base kit includes a vehicle-specific intercooler outlet pipe adapter and all necessary hoses, clamps, and fittings for a direct bolt-on installation on the GRB/GRF/GVB/GVF/VAB STI platforms
• Suction return kit (71002-AF002) included - routes compressed air released by the BOV back into the intake tract upstream of the MAF sensor, preserving the MAF signal and maintaining correct fueling under the deceleration and gear change conditions that trigger BOV actuation
• Iconic HKS SQV sound - produces the distinctive high-frequency metallic blow-off report characteristic of the HKS Sequential Blow Off Valve line, recognized as one of the most sought-after BOV tones in the performance car community
• Made in Japan by HKS

Specifications

• Part Number: 71008-AF013V
• Series: Super SQV4 (Super Sequential Blow Off Valve, 4th generation)
• Bundle Contents: Super SQV4 BOV Kit (71008-AF013) + Suction Return Kit (71002-AF002)
• Compatible Platforms: Subaru Impreza WRX STI GRB, GRF, GVB, GVF; Subaru WRX STI VAB/VAF
• Compatible Engines: EJ207 (2.0L turbo flat-4), EJ257 (2.5L turbo flat-4)
• Valve Operation: Pull-type sequential
• Pressure Control: Differential pressure control system
• Secondary Valve: Nickel-plated die-cast metal, swaged to primary valve
• Retention: Stainless steel C-clip
• Flange Compatibility: Same as all previous HKS SSQV generations
• CARB Legal: No - not for sale in California
• Country of Manufacture: Japan
• UPC: 4957266265611

Included Components

• 1x HKS Super SQV4 blow off valve head unit
• 1x vehicle-specific intercooler outlet pipe adapter
• 1x suction return kit (71002-AF002) - hose, fittings, and hardware for recirculation routing
• Hoses, clamps, and installation hardware

Product Description

The HKS 71008-AF013V is the Super SQV4 Sequential Blow Off Valve bundled with the suction return kit (71002-AF002) for the Subaru Impreza WRX STI across the GRB, GRF, GVB, GVF, and VAB/VAF platforms. The "V" suffix designates this as the bundle version; the base BOV kit without the return kit is sold separately as 71008-AF013. HKS introduced the first Sequential Blow Off Valve in 1994, establishing the pull-type sequential valve architecture that has since been widely imitated. The SQV4 is the fourth generation of this design - updated with a nickel-plated die-cast metal secondary valve swaged directly to the primary valve, a stainless steel C-clip for improved sealing retention, and a refined exterior design intended to differentiate genuine HKS units from counterfeit products, while the functional valve architecture and mounting flange dimensions remain compatible with all prior SSQV generations.

The core operating principle of the SQV4 is its differential pressure control system: the valve measures the pressure difference between intake manifold vacuum and intercooler pressure to determine precisely when and how far to open, rather than relying on a simple spring-loaded push threshold. This approach produces stable, consistent valve operation across the full range from light-throttle low-boost conditions to high-boost modified applications, without requiring tuning or adjustment for different boost levels. The pull-type relief design physically opens the valve by vacuum differential rather than boost pressure, giving more precise and predictable actuation timing than push-type designs.

The suction return kit bundled in the 71008-AF013V is essential for street use on the EJ207/EJ257 STI platforms, which use a mass airflow sensor (MAF). When a blow off valve vents to atmosphere on a MAF-based system, the metered air that the ECU has already accounted for is released rather than returned - causing the ECU to momentarily deliver excess fuel for air that is no longer entering the engine, which manifests as idle hunting, rich stumble, or stalling on deceleration. The return kit routes the blow-off air back into the intake tract upstream of the turbo inlet, ensuring the MAF signal remains accurate during BOV actuation events and maintaining smooth idle and fueling behavior on stock and tuned STI applications.