GrimmSpeed Bypass Valve - 2015-2021 WRX

SKU: 126023.2


2015-2021 Subaru WRX Bypass Valve by GrimmSpeed

We started the ground-up design with the valve body and base for each popular fitment. Both are CNC-machined out of billet 6061 aluminum alloy for their strength and light-weight. They are then anodized in either a black or red finish to give them a brilliant appearance, provide corrosion resistance and match other GrimmSpeed offerings. Compared to the stock cast unit on the EJ STI and plastic construction on both the 08-14 and 15-21 WRX platforms, GrimmSpeed Bypass Valves not only stand out but are guaranteed to stand the test of time.

For the internal components of the valve, we chose to utilize a machined brass piston for its anti-corrosion and low thermal expansion characteristics. Our piston seats onto an internal o-ring to create a perfect seal, eliminating boost leaks common in OEM and cheap aftermarket BPVs. In order to make sure this could keep up with high power levels, we chose to use a massive 38mm diameter piston/sealing ring for the ability to dump pressure quickly.

This is especially important in high boost applications to keep the turbo from sustaining damage and the BPV maintaining leak-free operation. A precisely-tuned steel spring alleviates the need for any tuning or adjusting of the valve, with no engine tuning required to run the unit. Buna-N O-rings were the next logical choice due to their resistance to degrading from fuel and oil exposure. In addition, all of our o-ring grooves utilize a single dovetail design for superior retention. This guarantees the o-ring will not fall out and has the perfect crush for sealing the body together. To top things off, we employ a swivel fitting on the valve to make for easy installation and accommodate best-routing on custom setups. A GrimmSpeed signature branding badge graces the top of each unit so that everyone will know you chose the best valve in the biz.

When designing the 15-21 WRX (FA) unit we paid special attention to the size. This was important due to the high number of hoses, wires, and hard parts needing to pass through this same compact space. We were able to keep the same large 38mm piston, but slim down the footprint of the valve making working in that area easier than with the factory part. With the GrimmSpeed Bypass Valve installed, a definite crispness and sound change is noticeable through the intake, and due to the leak-free nature of our valve, the car builds boost much more quickly than the leak-prone OEM version.


  • CNC-Machined 6061 Aluminum
  • Corrosion-resistant anodized finish, available in both red and black
  • Precision-tuned steel spring for long life
  • Single dovetail O-ring grooves with Buna-N O-rings for great oil resistance, retention, and leak-free operation
  • Swivel air fitting to aid in installation and for accommodating custom setups


  • Oversized 38mm brass piston for superior flow

Please Note: No tuning or adjustment is required.


  • 2015-2021 Subaru WRX

What's In The Box?

  • 1 - Bypass



  • GrimmSpeed's Limited Manufacturer's Warranty

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