Cobb Stage 1+ Power Package – Black – 2018-2021 Subaru STI

Cobb Stage 1+ Power Package — Black SF Intake — 2018-2021 Subaru STI

The Cobb Stage 1+ Power Package for the 2018-2021 Subaru STI includes the Cobb Accessport V3 and the Cobb SF Black Intake System. The Accessport provides EJ257-specific OTS calibration, and the SF black intake replaces the factory airbox with a cone filter and aluminum tube for improved airflow. The OTS map is calibrated specifically for the SF intake’s airflow characteristics on the EJ257 platform.

DETAILS

• Includes: Cobb Accessport V3 + Cobb SF Black Intake System
• Platform: 2018-2021 Subaru WRX STI EJ257 MT (inc. 2018 Type RA)
• SF Intake: cone filter, aluminum tube, black coupler — MAF retained in factory location
• OTS maps: 91 octane, 93 octane, E85 — EJ257 specific, calibrated for SF intake
• Improved mid-range responsiveness and boost delivery on EJ257 with SF intake
• Accessport live gauges: boost, AFR, IAT, coolant temp, and more
• Accessport data logging for ProTuner custom calibration
• NOTE: Ships via UPS/FedEx — signature required at delivery

EJ257 Stage 1+: Calibration, SF Intake, and How They Work Together

Stage 1+ for the EJ257 STI addresses the factory calibration’s conservatism in ignition timing advance, boost targets, and fuel strategy — the same approach Cobb takes across all turbocharged Subaru platforms. The EJ257 runs higher factory boost than the WRX FA20DIT, but still carries meaningful conservatism relative to what the engine can support on quality premium fuel, particularly in ignition timing where Subaru builds in margin for the global fuel quality spectrum. The SF intake replaces the factory airbox with a cone filter element and aluminum tube that improve airflow to the EJ257’s turbocharger. Cobb’s Stage 1+ OTS maps for the STI are calibrated specifically for the SF intake configuration — the calibration accounts for the SF intake’s improved airflow rather than applying a stock-airbox map with a filter change. The result is a calibration and intake working together as a validated system, producing improvement in mid-range responsiveness and more consistent boost delivery throughout the boost curve.

Boost Delivery, Gauge Monitoring, and the NexGen Stage 2 Foundation

The EJ257 STI responds to Stage 1+ calibration with sharper throttle response from off-throttle, more confident boost delivery through the mid-range, and more consistent power delivery to the top of the rev range. The Accessport’s live gauge display shows up to six parameters simultaneously — critical for an EJ257 build where monitoring IAT, coolant temperature, and AFR during spirited driving gives the driver real-time insight the factory STI instrument cluster does not provide. The black coupler provides a clean, understated engine bay appearance for owners who prefer performance components that do not call attention to themselves.

What’s in the Box

• Cobb Accessport V3
• Cobb SF Black Intake (filter, aluminum tube, black coupler, all hardware)
• OBD-II cable
• USB cable
• 2 faceplates
• Universal mount
• OTS maps — pre-loaded

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 2018-2021 STI represents the final development of the EJ257 platform, and it responds to Stage 1+ exactly as the platform has always responded to Cobb’s calibration and intake work — more willing, more responsive, and more rewarding to drive. Stage 1+ establishes the intake and calibration baseline that NexGen Stage 2 builds directly on. Building this correctly matters for how the build progresses.

Fitment

Year	Make	Model	Notes
2018-2021	Subaru	WRX STI	EJ257 MT
2018	Subaru	WRX STI Type RA	EJ257 MT