Grimmspeed V2 Bypass Valve – 2004–2021 Subaru WRX STI | Black

Upgrade the factory bypass valve on your 2004–2021 Subaru WRX STI with the Grimmspeed V2 Bypass Valve — a fully CNC-machined 6061 aluminum recirculating bypass valve engineered for the EJ257-powered STI across the GD, GR/GV, and VA chassis generations. The V2 is a significant redesign over the original Grimmspeed BPV, addressing the failure points identified in the V1 design with a lighter hard aluminum piston, redesigned internals, and refined spring tension for improved valve response and long-term reliability. No tuning or adjustment required — a direct plug-and-play upgrade over the factory valve.

V2 Improvements Over V1

• Hard Aluminum Piston: Lighter weight hard aluminum piston replaces the V1 brass piston — improved valve response and reduced reciprocating mass
• Redesigned Internal Piston: Eliminates the potential failure points identified in the V1 design for improved long-term reliability
• Refined Spring Tension: Adjusted internal spring tension based on further testing and development for better performance across the STI's operating environments
• Updated Main Body: Improved CNC milling finish on the main body for a cleaner, more precise appearance
• Inspection Port Removed: V1 inspection port removed — no longer required with the redesigned internals

Key Features

• CNC-Machined 6061 Aluminum: Precision CNC-machined from 6061 aluminum for superior strength, durability, and a premium underhood appearance
• 38mm Oversized Aluminum Piston: Oversized 38mm hard aluminum piston for superior flow capacity over the factory valve
• Black Anodized Finish: Corrosion-resistant black anodized finish for a clean, stealthy underhood look
• Swivel Air Fitting: Swivel air fitting aids installation and accommodates custom boost line setups
• No Tune Required: Direct plug-and-play replacement — no ECU tuning or adjustment required after installation
• Recirculating Design: Recirculates boost pressure back into the intake tract — maintains MAF sensor accuracy and avoids idle issues associated with atmospheric venting on MAF-based systems

Specifications

• Type: Recirculating Bypass Valve (BPV)
• Version: V2
• Material: CNC-Machined 6061 Aluminum
• Piston: 38mm Hard Aluminum
• Finish: Black Anodize
• Tune Required: No
• Fitment: 2004–2021 Subaru WRX STI (GD / GR / GV / VA) — EJ257
• Part Number: 126032BLK

Note: Recirculating bypass valve — not an atmospheric blow-off valve. Maintains factory MAF sensor accuracy for proper fuelling on the stock ECU. Also available in red for the 2015–2021 WRX (126033RED). Professional installation recommended.