GFB Respons Dual Port Variable BOV
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GFB Respons Dual Port Variable BOV - Subaru WRX/STI (GC8) MY94-96 / Toyota Supra (JZA80) - 20mm
GFB pioneered the dual port blow off valve back in 1999, and the Respons builds on that with a patented venting bias adjustment system. Rather than a fixed recirculate/atmosphere split, you dial in exactly how much air vents where, so the Subaru WRX, Subaru STI and Toyota Supra can all run a proper blow off sound without the stalling or over fuelling issues that plague simpler dual port valves on MAF equipped engines.
This listing covers the 20mm Respons TMS valve for the Subaru WRX (GC8) and Subaru STI (GC8) MY94-96, plus the Toyota Supra (JZA80) 1993-2002.
Note: WRX and STI GC8 fitment may require modification to factory hoses if mounting the valve elsewhere in the engine bay. The Supra JZA80 fitment is not a direct bolt-on and requires hose modification to install.
Key Features
- Patented venting bias adjustment, from full recirculation to full atmosphere venting
- Balanced piston design holds boost without blowing open under high pressure
- GFB TMS operating principle for faster boost recovery on gearshift
- 20mm valve port size
- Adjustable blow off sound to suit personal preference
Vehicle compatibility, OEM part numbers, and fitment notes are provided in the tabs above. Please confirm your vehicle's year and configuration before ordering.
Not sure if this valve suits your build? Contact our team at sales@chicaneaustralia.com.au for expert advice.
Vehicle Compatibility
| Make | Model | Chassis | Engine |
|---|---|---|---|
| Ford | Laser TX3 | KE | B6T |
| Ford | Laser TX3 | BG | B6T |
| Subaru | STI | GC8 | EJ20 |
| Subaru | WRX | GC8 | EJ20 |
| Toyota | Supra | JZA80 | 2JZ-GTE |
Technical Specifications
| Spec | Value |
|---|---|
| Valve Type | Dual Port Variable Blow Off Valve (BOV) |
| Port Size | 20mm |
| Piston Design | Balanced piston (boost pressure acts on both sides to prevent forced opening) |
| Venting Bias Adjustment | Continuously variable from 100% recirculation to 100% atmosphere venting |
| Boost Holding | Unlimited — not boost pressure limited, no spring changes required |
No instructions available for this product.

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