5 Best Subaru Blow off Valve Options Tested

I remember the first time I swapped out the factory bypass valve on my WRX—the instant rush of that distinct turbo flutter was addictive. But choosing the right valve isn’t just about the sound; it’s crucial for maintaining boost integrity and protecting your turbocharger. We’ve spent time reviewing and testing several options to help you find the best subaru blow off valve that fits your driving needs and budget, focusing heavily on fitment for popular models like the WRX and STI.

IMAGE	PRODUCT NAME	AMAZON LINK
	Blue Aluminum Dual Port Blow Off Valve (BOV) Dump Valve…	View on Amazon
	Car Blow Off Valve Spacer Fit For Sub-aru For Impreza…	View on Amazon
	Aluminum Adjustable Blow Off Valve Kit for 2002-2007 Subaru…	View on Amazon
	‎Embellu K5T09795 Air Bypass Blow Off Valve BOV Compatible…	View on Amazon
	Angle Flange Blow Off Valve For Subaru 02-07 IMPREZA WRX…	View on Amazon

Blue Aluminum Dual Port Blow Off Valve (BOV) Dump Valve for Mazdaspeed 3 (2007-2013), Mazdaspeed 6 (2005-2007), CX-7 (2006-2012), Subaru WRX (2008-2014), Forester XT (2008-2012)

This dual-port blow off valve is a visually striking and functional upgrade for several popular Subaru models, including the 2008-2014 WRX. Its 50/50 venting ratio offers a desirable blend of recirculation and atmospheric venting, delivering that classic turbo sound without completely disrupting the MAF readings. The unit is crafted from durable, corrosion-resistant aluminum, ensuring it handles high boost pressure reliably and adds a vibrant blue aesthetic under the hood.

Key features that stand out:

• Premium Aluminum Construction: Crafted from high-quality aluminum for long-lasting durability.
• 50/50 Dual Port Design: Provides a balanced sound profile while maintaining smoother idle performance.
• Wide Compatibility: Fits 2008-2014 WRX and Forester XT (EJ25 models).

Pros:
– Striking blue finish adds aesthetic appeal.
– Dual port setup offers excellent sound without major tuning issues.
– Robust construction ensures reliability under high boost.

Cons:
– Professional installation is strongly recommended as instructions aren’t included in the box.

Best for: Drivers seeking the classic blow off sound on older WRX/Forester models who value a mix of performance and aesthetics.

Expert Opinion: This valve is a solid choice for those wanting to move away from the stock bypass valve but maintain some recirculation for smoother idle operation, especially on MAF-based systems like the older WRX.

Car Blow Off Valve Spacer Fit For Sub-aru For Impreza for WRX STi 2015-2020 Air Bypass Blow Off Valve, Replacement Part Number 14471AA143 14471-AA143

This component is designed specifically for 2015-2020 WRX and STi models, acting as either a direct air bypass replacement or used in a spacer setup. Constructed from sturdy, high-grade metal, it ensures the unit can withstand repeated pressure cycles without warping or failing, offering exceptional durability. It’s engineered for quick replacement, making installation significantly simpler than a full aftermarket BOV swap.

Key features that stand out:

• Sturdy Metal Materials: Constructed from high-grade metal for reliable durability under pressure.
• Hassle-Free Installation: Engineered for easy replacement installation with minimal fuss.
• OE Replacement Fitment: Specifically designed to match replacement part number 14471AA143.

Pros:
– Direct fit for modern FA/EJ engines (2015+ platforms).
– Highly durable and resistant to deformation.
– Maintains OE engine characteristics and tuning stability.

Cons:
– Does not provide the loud, aggressive sound of a true atmospheric blow off valve.

Best for: Owners of newer Subarus (2015-2020) seeking a highly durable OE replacement or a mild, subtle sound modification via a spacer setup.

Expert Opinion: While technically listed as a replacement valve, its main appeal often lies in its use as a mounting point for a spacer kit to provide a subtle “whoosh” sound. Always verify the OE number on your vehicle before purchase, especially since modern Subarus have stricter engine management requirements.

Aluminum Adjustable Blow Off Valve Kit for 2002-2007 Subaru WRX, 2004-2017 STI – Boost Control, Turbo Protection

This adjustable blow off valve kit is a favorite for the long-running EJ platform, offering precise control over boost release and turbo health. Made from high-grade aluminum, its design actively prevents compressor surge, a leading cause of premature turbo failure, especially during high-boost driving. The key selling point is the ability to independently control both relief pressure and the volume of air vented, giving you total customization for your driving style.

Key features that stand out:

• Performance Enhancing Design: Features a larger outlet designed to eliminate compressor surge.
• Customizable Air Volume Control: Allows independent adjustment of air volume released for optimal shift points.
• Precise Vehicle Fitment: Specifically engineered to fit a wide range of EJ models, including 2004-2017 STI.

Pros:
– Highly adjustable for fine-tuning performance and sound.
– Excellent focus on turbocharger protection and longevity.
– Comprehensive kit includes all necessary accessories for installation.

Cons:
– Requires significant tuning knowledge to properly optimize the adjustable settings for peak performance.

Best for: Enthusiasts running higher boost levels who need fine-grained control and maximum turbocharger protection on classic EJ platforms.

Expert Opinion: The ability to adjust air volume independently is fantastic for achieving the perfect balance between aggressive sound and maintaining drivability. This is one of the most versatile best subaru blow off valve options for older, heavily modified cars.

‎Embellu K5T09795 Air Bypass Blow Off Valve BOV Compatible with 2015-2019 Subaru WRX STI

This unit serves as a direct OE replacement bypass valve for specific 2015-2019 WRX STI models, ensuring seamless integration with the factory ECU. Utilizing an exact replacement part is critical for avoiding engine lights or tuning issues prevalent in newer, sophisticated engine management systems. While functionally stock, its benefit lies in ensuring the integrity of the boost system if your original valve has failed or become sticky, which often leads to inconsistent boost pressure.

Key features that stand out:

• OE/OEM Part Number K5T09795: Provides a direct factory-spec replacement.
• Critical Fitment Check: Must match the OE number and appearance to guarantee compatibility.
• Reliable Functionality: Restores and maintains factory boost management and vacuum retention.

Pros:
– Factory-level function and fitment guarantee.
– Ideal for routine maintenance or repairing a failing boost system component.
– High compatibility assurance if the OE number matches.

Cons:
– Offers zero performance or sound enhancement compared to the original stock unit.

Best for: Owners who need a reliable, cost-effective replacement for a failed or aging factory bypass valve on a 2015-2019 WRX STI.

Expert Opinion: This type of valve is essential for maintaining the factory tune. If you aren’t planning on running an aggressive aftermarket tune or need the distinct blow off sound, replacing the existing valve with this OE-spec part is the wisest reliability move.

Angle Flange Blow Off Valve For Subaru 02-07 IMPREZA WRX STI SQV SSQV HKS BOV

Modeled after the highly popular Sequential Blow Off Valve (SSQV) design, this angle flange unit is specifically tailored for 2002-2007 Impreza WRX STI models. This design is highly coveted for the distinct, high-pitched sequential venting sound it produces upon throttle lift. It utilizes a secure angular flange mount, which is critical for a leak-free installation on the older EJ engine platforms. This is the valve you choose when sound is your absolute priority.

Key features that stand out:

• Sequential Venting Design: Produces the iconic, high-pitched “chirp” sound.
• Angle Flange Fitment: Ensures a secure, direct fit onto 02-07 EJ platforms (GDB GDA EJ20/EJ25).
• Iconic Aesthetic: Visually recognizable style often associated with high-performance builds.

Pros:
– Delivers the loudest, most recognizable blow off valve sound.
– Excellent build quality for a flange-style unit.
– Secure connection helps prevent boost leaks.

Cons:
– Running a fully atmospheric BOV on MAF-based systems may require tuning to prevent running rich between shifts.

Best for: Drivers of 02-07 WRX/STI models prioritizing the loudest, most recognizable blow off valve sound and aesthetic.

Expert Opinion: While often referred to as a “clone” of a famous Japanese design, this valve offers excellent performance and sound characteristics for the price point. Just be aware that moving to a fully atmospheric system, even with the best subaru blow off valve setup, might require some ECU attention.

Helpful Comparison Short Insights

When evaluating the options for the best subaru blow off valve, it’s crucial to separate models by their required use.

For 2015-2020 WRX/STI owners, the focus should be on fitment reliability due to the sensitive FA engine ECU. Options like the Embellu K5T09795 (direct replacement) or the Car Blow Off Valve Spacer are the most direct fits, prioritizing OEM integrity and durability, respectively, over aggressive noise.

If you drive a classic 2002-2007 EJ WRX/STI, you have the most flexibility for performance and sound. Here, the Aluminum Adjustable Blow Off Valve Kit provides maximum control and turbo protection, making it ideal for tuned cars. Conversely, the Angle Flange Blow Off Valve is purely for maximum sound output.

The Blue Aluminum Dual Port BOV offers a solid middle ground for those with a slightly newer WRX (2008-2014) who want performance sound without the full atmospheric complications that can cause stumbling on MAF-based systems. Dual port valves often strike the best balance between sound and drivability.

Final Verdict: Which Subaru Blow Off Valve Wins?

Choosing the best subaru blow off valve truly depends on your chassis and goals. If control, fine-tuning, and long-term turbo longevity are your main priorities for an older EJ platform (2002-2017 STI), the Aluminum Adjustable Blow Off Valve Kit is the clear winner due to its unparalleled fine-tuning capabilities against compressor surge.

However, for those driving a 2015+ platform looking for reliable OE replacement or the easiest installation, the Car Blow Off Valve Spacer provides simple, robust functionality that you can trust. It’s the smart choice for daily drivers.

Common Questions About Best Subaru Blow off Valve

Does installing a blow off valve require ECU tuning on a Subaru?

It depends entirely on the Subaru model and the type of valve. Older Subarus (pre-2015 WRX/STI) often use a Mass Airflow Sensor (MAF) which measures all incoming air. When a fully atmospheric blow off valve vents air to the atmosphere, the MAF sensor thinks that air is still entering the engine, causing a brief moment where the car runs rich. While some users skip tuning, professional ECU tuning is highly recommended for any fully atmospheric valve to maintain optimal performance and prevent potential drivability issues. Recirculating or dual-port valves usually require less tuning intervention.

What is the difference between a bypass valve and a blow off valve (BOV)?

Functionally, both types of valves release excess boost pressure when the throttle closes to prevent damaging the turbo. A bypass valve (BPV), which comes stock on most Subarus, recirculates the vented air back into the intake system before the turbocharger. A blow off valve (BOV) vents the pressurized air directly into the atmosphere, creating the loud “whoosh” sound.

Will a blow off valve hurt my Subaru’s turbocharger?

No, a quality blow off valve actually protects your turbocharger. By releasing high pressure quickly upon throttle lift, the valve prevents pressure from flowing backward against the compressor wheel. This backward pressure is known as compressor surge (or turbo flutter), which stresses the bearings and can significantly shorten the lifespan of the turbo.

Which subaru blow off valve setup offers the best balance of sound and reliability?

For most MAF-based Subaru engines, a dual port or 50/50 valve offers the best balance. Valves like the Blue Aluminum Dual Port BOV vent some air atmospherically for sound, but recirculate the rest. This minimizes the measured air loss that can confuse the MAF sensor, helping to maintain smoother idling and shift points without requiring an immediate custom tune.

Are fully atmospheric BOVs street legal?

The legality of fully atmospheric blow off valves varies by state and country, particularly regarding emissions laws. In some areas, venting metered air to the atmosphere can be seen as bypassing or disrupting the factory emissions system. Always check your local regulations, but generally, OE-style recirculating bypass valves are the safest option for maintaining emissions compliance.

How difficult is it to install a best subaru blow off valve?

Installation difficulty ranges from simple to complex. Direct OE replacement bypass valves (like the Embellu unit) are generally bolt-on and straightforward, often requiring just basic tools. Full aftermarket blow off valves or flange-mounted units (like the Angle Flange BOV) are more involved and may require removing other components, relocating vacuum lines, and ensuring the complex boost control system is sealed correctly. If you are unfamiliar with turbo systems, professional installation is advised.