Cobb Tuning SF Air Box – 2019-2021 Subaru STI / 2018 STI Type RA

Description:

Cobb SF Intake Air Box 2015-2021 Subaru STI

The Cobb SF Air Box for the 2015-2021 Subaru STI replaces the factory airbox with a performance unit that improves airflow to the EJ257 while maintaining an enclosed air path.

DETAILS

• Cobb SF Intake System
• Platform: 2015-2021 Subaru WRX STI
• High-flow cone filter larger surface area than OEM panel filter
• Polished aluminum intake tube smoother airflow path than factory plastic
• MAF sensor retained in factory-equivalent position for accurate air mass measurement
• Designed for use with Cobb Accessport SF intake OTS maps
• All mounting hardware and couplers included

SF Intake Design: Filter, Tube, and MAF Positioning

The Cobb SF Intake System replaces the factory air intake assembly airbox, filter, and intake tube with a purpose-designed short-ram intake built around a high-flow cone filter element and a smooth polished aluminum intake tube. The factory intake assembly uses a panel air filter that limits airflow, a plastic airbox that absorbs engine bay heat into the intake air, and an intake tube with bends and diameter changes that create turbulence and restriction in the air path to the turbocharger inlet. The SF intake addresses all of these limitations: the cone filter has significantly more filter surface area than the OEM panel filter, providing improved airflow capacity and reduced restriction across the operating range. The aluminum tube runs a smoother, straighter path to the turbocharger inlet with better internal geometry for laminar airflow. The MAF sensor is relocated to the SF intake tube in the correct location for accurate air mass measurement, maintaining proper fueling across all conditions.

Accessport Map Integration and Installation

The SF Intake is designed to be used with a Cobb Accessport OTS map calibrated specifically for the SF intake configuration the map accounts for the SF intake's improved airflow characteristics, the MAF sensor position in the new tube, and the change in intake air temperature behavior that comes from the more open intake system. Installing the SF intake without a corresponding calibration change produces suboptimal results because the stock ECU map is calibrated for the restricted flow of the factory intake. With the correct SF intake OTS map loaded on the Accessport, the intake and calibration work together as a validated system, and the improvement in throttle response, boost ramp, and mid-range power reflects the full potential of the SF intake upgrade.

What's in the Box

• Cobb SF Intake System (filter, tube, couplers, all hardware)

Why Choose Cobb Tuning

Cobb Tuning has been developing performance software and hardware for turbocharged enthusiast vehicles since 1999. Founded in Austin, Texas, Cobb built its reputation on the Accessport and expanded into a full catalog of hardware engineered to complement it. Every OTS map is developed in-house on real vehicles, and every hardware product is validated as part of a complete system not sourced and sold in isolation. That integrated approach is why Cobb produces consistent, reliable results across the builds we see every day.

The RallySport Take

The Cobb SF Intake for 2015-2021 Subaru WRX STI is the correct intake upgrade for builds running the Cobb Accessport. The SF intake OTS maps loaded on the Accessport are calibrated for this specific intake system install the intake, load the corresponding OTS map, and the system works correctly from the first drive.

Fitment