Subaru LF Bypass Valve WRX 2015-2020, FXT 2014-2018

$ 325.00

Availability: Ships in 24 hours
Product Code: 745670

California Residents: Prop 65 Warning

Free Shipping

This part is legal under the provisions of EPA’s Anti-Tampering Policy. COBB Tuning has established a reasonable basis (testing results) to verify that this product allows the vehicle to operate within legal emissions standards and is therefore legal to be sold for on-street use in all states that accept the legal provisions of the Clean Air Act and EPA’s Anti-Tampering Policy.


Testing with the California Air Resources Board, in order to achieve 50-state compliance, is pending. Once testing is complete with California, and an EO number is issued, this product will be updated to 50-state legal status.


The COBB LF BPV is a compact and lightweight by-pass valve that is capable of holding very high boost pressure without leaking. Its updated design reduces control volume by 30% allowing for extremely fast venting of boost when actuated. Innovative engineering and precision manufacturing result in a compact package able to fit in the confines of a tight engine bay. Due to the low weight of the components, the moving parts in the LF BPV have less inertia and can respond faster than heavier components in other bypass valves. This updated design uses a Banjo-fitting vacuum port which provides 360 degree adjustability of hose routing. This results in a simpler install and less potential leak points than the NPT ports. This new design also includes a piston o-ring seal that is twice the diameter of the old design allowing more seal compression and reduced wear. Adjustability of the spring seat is no longer needed due to the updated spring and seal design which provides a 60% increase in clamping force at peak boost while maintaining similar operation at idle and transient loads.

Note: This is an updated version of the original 745665 LF BPV that now includes a different internal spring.

Original Spring (uncoated)
Free length: 3.5"
Rate: 7.4 lbf/in
Bench cracking vacuum installed in LF BPV: -5.7 psi

New Spring (yellow)
Free length: 2.25"
Rate: 40.5 lbf/in
Bench cracking vacuum installed in LF BPV: -6.7 psi


A compact and very lightweight bypass valve that is loaded with features and reliability holds high levels of boost without leaks.

Subaru LF Bypass Valve WRX 2015-2020, FXT 2014-2018
  • 100% Billet Aluminum Construction
  • 100% O-Ring Sealing
  • 100% Rebuildable if there ever is an o-ring failure

Customer Photos