HKS 71008-AF015 Super SQV4 Blow Off Valve + Return Kit for 2015-2021 Subaru WR

Vehicle Fitment

• 2015-2021 Subaru WRX Sedan (VA body - VM4 platform, FA20DIT 2.0L turbocharged direct injection flat-4, AWD - all trims)
• 2014- Subaru Levorg (VMG platform - FA20 turbocharged flat-4, AWD) - JDM market
• 2014- Subaru WRX S4 (VAG platform - FA20 turbocharged flat-4, AWD) - JDM market

Fitment Notes

• This kit is for the Subaru WRX (non-STI) with the FA20DIT engine only. It does NOT fit the Subaru WRX STI (VAB/VAF), which uses the EJ207 or EJ257 engine and a different BOV/intercooler pipe configuration. The WRX STI uses HKS 71008-AF013V
• The VA-body WRX (VM4) and WRX STI (VAB/VAF) share the same external body style but have fundamentally different drivetrain, turbo system, and intercooler piping layouts - the BOV mounts to different locations and uses different adapters on each platform
• Suction return kit is included as standard - the kit can be configured as a recirculating system (return to intake, MAF-safe) or as an atmospheric vent depending on installation preference and tune
• Can be run on a stock ECU in recirculating configuration - routing the blow-off air back into the intake tract preserves the MAF signal and prevents the rich stumble, idle hunting, or stalling that occurs when metered air is vented to atmosphere on a MAF-based system without ECU recalibration
• This product is not CARB legal and is not for sale in California

Features

• Dual sequential valve structure - the SQV4 uses two valves in series: a small primary valve that opens first for ultra-fast actuation at light-load and low-boost conditions, followed immediately by a larger secondary valve that opens to discharge the full volume of excess boost pressure. This sequential approach solves the trade-off between fast response and high discharge capacity that single-valve designs cannot achieve simultaneously
• Pull-type relief valve operation - the valve is held closed by boost pressure acting on the valve face when on-throttle, making it essentially impossible to boost-leak under load. On deceleration, the vacuum differential pulls the primary valve open. Because boost pressure actively seals the valve, the SQV4 becomes more reliably sealed as boost increases, rather than less
• Differential pressure control system - measures the pressure differential between the intercooler side and the intake manifold vacuum to determine opening timing and degree, enabling stable, consistent actuation across the full range from idle to peak boost and from stock tune to significantly elevated boost levels
• Triple fin design - the three-fin internal geometry of the secondary valve produces the characteristic sharp, high-frequency SQV sound on discharge - one of the most recognized and sought-after BOV tones in the performance car segment
• High quality aluminum die-cast body - lightweight, rigid, and corrosion-resistant; the die-cast construction provides precise internal tolerances for consistent valve sealing and actuation
• High stiffness metal die-cast valve - the internal valve components are metal die-cast rather than plastic or stamped metal, providing superior dimensional stability and durability under sustained high-temperature, high-pressure cycling
• Silver finish - the polished silver aluminum body provides a clean, premium engine bay appearance and is designed to be positioned visibly beside the engine for visual impact as well as function
• Suction return kit included as standard - all hardware required to configure the BOV for recirculating (MAF-safe) or atmospheric operation is included in the box
• Compatible with optional atmospheric vent configuration - if the vehicle is running a speed density tune (MAP-sensor based) rather than MAF-based fueling, the kit can be configured to vent to atmosphere for maximum response and the full audible SQV effect
• Vehicle-specific pipe adapter and hardware - includes the application-specific intercooler outlet adapter for the FA20DIT WRX and all hoses, clamps, and fittings for a complete bolt-on installation
• Made in Japan by HKS

Specifications

• Part Number: 71008-AF015
• Series: Super SQV4 (Super Sequential Blow Off Valve, 4th generation)
• HKS Product Name: Super SQV4 Return Kit Plus VMG/VM4
• Compatible Platforms: Subaru WRX VM4 (US 2015-2021); Subaru Levorg VMG; Subaru WRX S4 VAG
• Compatible Engine: FA20DIT (2.0L turbocharged direct injection flat-4)
• Valve Operation: Pull-type sequential (dual valve - primary + secondary)
• Pressure Control: Differential pressure control system
• Valve Body: High quality aluminum die-cast, silver finish
• Internal Valve: High stiffness metal die-cast
• Sound Design: Triple fin
• Suction Return Kit: Included as standard
• Configuration Options: Recirculating (MAF-safe) or atmospheric
• CARB Legal: No - not for sale in California
• Country of Manufacture: Japan
• UPC: 4957266265505

Included Components

• 1x HKS Super SQV4 blow off valve head unit (silver, aluminum die-cast)
• 1x vehicle-specific intercooler outlet pipe adapter for FA20DIT WRX/Levorg/WRX S4
• Suction return kit hardware (hose, fittings for recirculating configuration)
• Hoses, clamps, and complete installation hardware

Product Description

The HKS 71008-AF015 is the Super SQV4 Sequential Blow Off Valve with suction return kit for the 2015-2021 Subaru WRX (VM4, FA20DIT), the JDM Levorg (VMG), and the JDM WRX S4 (VAG). This kit is specific to the FA20DIT-powered WRX and is not interchangeable with the WRX STI application (71008-AF013V), which uses a different intercooler outlet pipe adapter and hardware suited to the EJ207/EJ257 turbo system. Despite sharing the same VA-body shell, the WRX and WRX STI have entirely distinct turbo and intercooler piping layouts, and the BOV mounts to different locations on each vehicle.

The SQV4's defining engineering feature is its dual sequential valve architecture. A small primary valve opens first under any deceleration event - responding quickly even at light throttle and low-boost conditions where a single large valve would react too slowly or not at all. As the pressure differential increases, the larger secondary valve opens to handle the full discharge volume. This two-stage approach provides both ultra-fast initial response and the high flow capacity needed to properly relieve boost at elevated pressure levels - characteristics that are mutually exclusive in single-valve designs. The triple-fin internal valve geometry produces the SQV series' signature sharp, high-frequency discharge sound, while the aluminum die-cast body and metal die-cast internal valve components provide the structural durability expected from a valve that will cycle many thousands of times under turbo operating conditions.

The suction return kit is included and is configured at installation - the system can run in recirculating mode, where blow-off air is returned to the intake tract upstream of the turbo inlet to preserve the factory MAF signal, or in atmospheric mode if the vehicle is running a speed density (MAP sensor) tune. In recirculating configuration, the 71008-AF015 is compatible with a stock ECU and factory tune on the FA20DIT WRX, making it accessible as an upgrade even for untuned vehicles. For owners who choose to run the kit atmospheric, appropriate ECU recalibration is needed to account for the loss of metered air during BOV actuation events.