Nice Upgrade
A must have before getting a pro-tune. Elite Race Fab seems to have the lowest prices along with fast shipping.

The Cobb 04–07 Subaru STI / 02–07 WRX / 04–08 Forester XT 3-Port Boost Control Solenoid (Part#: 712750) is a precise and reliable boost control upgrade designed to provide improved boost response and consistency over the factory solenoid. The 3-port configuration gives tuners greater control of boost levels, making it ideal for vehicles with intake, exhaust, or turbo upgrades.
Engineered with fast solenoid response, durable construction, and direct-fit connectors, it integrates seamlessly with OEM wiring and ECU tuning strategies for stable, predictable boost management.
Cobb 3-port boost solenoid, Subaru WRX STI boost control, Forester XT EBCS upgrade, turbo boost solenoid, Cobb boost management component (712750)