Specifications
Part Details:
Tuning required. Installing this kit requires a custom tune or an appropriate COBB Stage Power Package map that specifically includes support for this kit. Consult with COBB or an authorized ProTuner before installing.
On the 2008 and newer STI, the fuel pressure regulator references vacuum and boost from a single cylinder runner, cylinder #4, which can create pulsations that affect fuel pressure stability under certain conditions. This COBB kit relocates that reference line to a plenum-based source instead, mirroring the more stable design used on the earlier 2004-2007 STI. Since the plenum represents the averaged vacuum and boost across all cylinders rather than a single one, this change reduces unwanted pulsation and delivers more consistent fuel pressure to the injectors.
The kit includes a reducing “T” fitting (4mm and 6mm) along with the hose and hardware needed to complete the relocation.
Key Features
- Fits 2008 to 2021 Subaru STI
- Relocates the FPR reference line from cylinder #4 to a plenum-based source
- Reduces manifold pulsation for more consistent fuel pressure
- Mirrors the reference design used on the 2004-2007 STI
- Includes reducing T fitting and installation hardware
- Requires custom tuning or a compatible COBB Stage Power Package map
- Not an emissions-related part, legal in all 50 states
Frequently Asked Questions
Do I need a tune to install this?
Yes. This kit requires a custom tune or an appropriate COBB Stage Power Package map that includes support for the relocation. Do not install without confirming tuning compatibility first.
Does this fit the WRX?
No, this kit is designed specifically for the 2008 to 2021 Subaru STI.
What problem does this actually solve?
It addresses fuel pressure pulsations caused by referencing a single cylinder runner, replacing it with a more stable, averaged plenum-based reference for more consistent fuel delivery.
Recommended Supporting Components
- STI Fuel System Upgrades explore injectors, fuel pumps, and fuel delivery upgrades for your STI build.
- COBB Accessport for WRX and STI: What It Does and Is It Worth It need a tuning platform for this install? Start here.
Why Buy Fuel System Upgrades from Wrench Masters?
Wrench Masters carries the fuel system refinements that support a properly tuned build, not just the bolt-on basics. This kit is a proven upgrade for anyone already working with a qualified tuner.
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Delivery Times:
- In Stock: 3-7 Business Days
- Custom Orders: 2-6 Weeks, Please Email: [email protected] or Call: 727-565-9808 for Questions.
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