Invidia 08-19 WRX/STI Down-Pipe w/ High Flow Cat - HS08SW1DOCB

The Invidia High Flow Cat Downpipe (HS08SW1DOCB) is a direct-fit performance exhaust upgrade engineered specifically for the 2008–2019 Subaru WRX and STI. Replacing the restrictive factory downpipe is one of the most impactful bolt-on modifications available for these turbocharged Subarus, and Invidia's reputation in the enthusiast community makes this one of the most sought-after options in that segment. By pairing a less restrictive exhaust path with an integrated high-flow catalytic converter, this downpipe helps your EJ or FA engine breathe more freely while retaining emissions hardware for street-driven builds.

Key Features & Benefits

• High-Flow Catalytic Converter Included: The integrated high-flow cat reduces exhaust backpressure compared to the stock cat while retaining a catalytic converter in the exhaust stream — a practical choice for owners who want improved flow without going fully catless on a street car.
• Direct Replacement for the Factory Downpipe: Designed as a direct-fit upgrade for 2008–2019 WRX and STI platforms, reducing installation complexity versus custom or universal solutions.
• Invidia Build Quality: Invidia is a well-established brand in the Subaru performance exhaust space, known for producing parts that balance performance and street usability across their WRX/STI lineup.
• Street-Friendly Performance Upgrade: The high-flow cat option is an ideal middle ground for daily-driven or lightly modified WRX and STI builds — improved exhaust scavenging without sacrificing the catalytic converter entirely.
• Compatible with Invidia Adapter: For owners pairing this downpipe with an existing 2.5-inch cat-back exhaust system, Invidia offers the HS02SWIAPD 3-inch to 2.5-inch downpipe adapter as a companion piece (sold separately).

Specifications

• Brand: Invidia
• Part Number (MPN): HS08SW1DOCB
• SKU: INVHS08SW1DOCB
• Catalytic Converter: High-flow cat included
• CARB Status: NOT CARB legal — not for sale or use in California
• Emissions Note: This product is not CARB legal and is intended for off-road or racing use, or use in states that do not follow California emissions standards. Check your local regulations before purchasing.

Fitment

This downpipe is designed to fit the following vehicles:

• 2008–2019 Subaru WRX
• 2008–2019 Subaru STI

Does NOT fit: The 2015–2021 WRX with manual transmission uses a different Invidia downpipe (HS15SWMDOCB). The 2002–2007 Subaru WRX/STI also uses a separate part (HS05SW1DOC). The 2022+ WRX platform is not covered by this fitment. Always confirm your specific model year and transmission before ordering.

Important California Note: This product is not for sale in the state of California due to CARB emissions regulations.

What's in the Box

• Invidia high-flow cat downpipe assembly (HS08SW1DOCB)

Note: Hardware and gaskets — confirm with the manufacturer's installation documentation. An optional 3-inch to 2.5-inch exhaust adapter (HS02SWIAPD) is available separately if needed for your cat-back system.

Why Buy from ThreePiece.us

• Free Shipping: Every order ships free — no minimum threshold required.
• Affirm Financing: Split your purchase into manageable payments with Affirm, so you can upgrade your WRX or STI exhaust system now without paying everything upfront.
• Fitment Expertise: Not sure if this downpipe is the right fit for your specific build year, trim, or cat-back exhaust setup? Our team is here to help you get the right part the first time.
• Enthusiast-Focused Retailer: We carry a curated selection of proven performance exhaust and drivetrain parts, so you're not sifting through irrelevant catalog filler to find what your Subaru actually needs.

Frequently Asked Questions

Q: Will this downpipe fit my 2015–2019 WRX with a manual transmission?
A: The HS08SW1DOCB covers the 2008–2019 WRX and STI, which includes those years. However, Invidia also offers a dedicated J-pipe downpipe specifically for the 2015–2021 WRX with manual transmission (HS15SWMDOCB). If you have a 2015–2019 manual WRX, it's worth confirming which fitment applies to your chassis before ordering — our team can help clarify.

Q: Does this downpipe include a catalytic converter?
A: Yes. The HS08SW1DOCB comes with an integrated high-flow catalytic converter. This makes it a popular choice for street-driven WRX and STI owners who want improved exhaust flow while keeping a cat in the system.

Q: Can I use this downpipe in California?
A: No. This product is not CARB legal and is explicitly not for sale in California. It is intended for use in states that do not follow California emissions standards, or for off-road/competition use where permitted. Please check your local and state regulations before purchasing.

Q: Will this downpipe work with my existing 2.5-inch cat-back exhaust?
A: Invidia offers a 3-inch to 2.5-inch downpipe adapter (part number HS02SWIAPD) specifically to connect this downpipe to a 2.5-inch cat-back exhaust system. This adapter is sold separately. If you're unsure about compatibility with your specific cat-back, contact us before ordering.