Invidia 3in Downpipe to 2.5in Exhaust Adapter - Subaru Models (Inc. 2008-2021 Subaru WRX / STI / 2004-2010 Forester)

The Downpipe: Where Stage 2 Starts on the GR STI

The Invidia Catted Downpipe for the 2008-2014 Subaru WRX STI replaces the factory downpipe with a 3-inch stainless steel unit. The high-flow catalytic converter maintains emissions compliance while significantly outflowing the restrictive factory unit. A tune is required after installation.

High-Flow Cat: Compliant and Free-Flowing

The high-flow catalytic converter included in this downpipe flows significantly more exhaust gas than the factory unit while maintaining catalytic function. For builds requiring a street-legal exhaust, the catted downpipe provides the majority of the performance benefit of a catless unit while keeping the vehicle compliant in most jurisdictions outside California.

3-Inch Stainless, Bolt-In at OEM Turbo Flange

The Invidia downpipe connects at the factory turbocharger outlet flange and runs to the factory cat-back connection point. 3-inch mandrel-bent 304 stainless steel throughout. Factory O2 sensor bung positions are retained. Additional O2 bung included for wideband sensor. A tune is mandatory after installation.

Key Features

• Platform: 2008-2014 Subaru WRX STI
• 304 stainless steel, 3-inch mandrel-bent piping
• High-flow catalytic converter — emissions compliant (not CARB legal)
• Extra O2 bung for wideband sensor
• Bolt-in at factory turbocharger outlet flange
• Compatible with OEM and aftermarket cat-back exhaust systems
• TUNE REQUIRED — do not run on stock ECU calibration

Fitment Notes

• Platform: 2008-2014 Subaru WRX STI
• MT and CVT compatible — confirm by SKU
• TUNE REQUIRED after installation
• NOT CARB legal — cannot ship to California
• Does not include turbo-to-downpipe gasket — source separately

Straight From Subispeed

The Invidia catted downpipe is the correct first major exhaust upgrade on the GR STI for owners who need to keep the car street-legal. The high-flow cat outflows the stock unit significantly while maintaining emissions compliance in most states outside California. A tune is not optional with this installation — running any aftermarket downpipe on the stock ECU calibration is a reliability concern, not just a performance one.

What's Included

• Invidia Catted Downpipe
• High-flow catalytic converter
• New exhaust gasket and hardware
• NOTE: Does not include turbo-to-downpipe gasket — source separately

About Invidia

Invidia is a Taiwanese performance exhaust manufacturer with a strong following in the Subaru, Mitsubishi, and Japanese sports car communities. Their catalog covers cat-back exhausts, downpipes, headers, manifolds, and full exhaust systems built around SUS304 stainless steel construction with CNC-machined flanges and direct OEM fitment. Invidia exhausts are among the most widely installed aftermarket systems on Subaru platforms globally — well-documented, well-supported, and proven across thousands of street and track builds. Subispeed carries the full Invidia lineup because their combination of quality construction, fitment accuracy, and range of tip and finish options makes them the exhaust brand we recommend to Subaru owners at nearly every power level.