LF By-Pass Valve

• 2014-2018 Subaru | Forester XT
• 2015–2021 Subaru | WRX

The COBB LF BPV is a compact, lightweight by-pass valve engineered to hold high boost pressure without leaking. Its updated design reduces control volume by 30% for faster venting, while the banjo-fitting vacuum port provides 360-degree hose-routing adjustability. Lightweight moving parts reduce inertia, and the updated spring and seal increase peak clamping force by 60% while maintaining similar idle and transient operation.

• 100% billet aluminum construction with 100% O-ring sealing.
• Fully rebuildable if an O-ring ever needs replacement.
• Updated version of the original 745665 LF BPV with a different internal spring.
• Original spring: 3.5-inch free length, 7.4 lbf/in rate, and -5.7 psi bench cracking vacuum; new yellow spring: 2.25-inch free length, 40.5 lbf/in rate, and -6.7 psi bench cracking vacuum.
• Confirmed fitment: 2015-2021 Subaru WRX and 2014-2018 Subaru Forester XT. Verify the exact vehicle configuration before installation.
• 50-state emissions legal when used according to the COBB application guide; covered by CARB Executive Orders D-660-36 and D-660-83.
• Installation difficulty is approximately 2 out of 5. Installation instructions.
• Official video: Inside the COBB LF Bypass Valve.
• References: Official COBB product page, CARB D-660-36, and CARB D-660-83.

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• COBB MFG Warranty

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