COBB Tuning Subaru Stage 1+ Redline Carbon Fiber Power Package – 2015-2021 Subaru STI

Cobb Stage 1+ Redline Carbon Fiber Power Package — 2015-2021 Subaru STI

The Cobb Stage 1+ Redline Carbon Fiber Power Package for the 2015-2021 Subaru STI pairs the Cobb Accessport V3 with the Cobb Redline Carbon Fiber Intake. The carbon fiber construction reduces heat soak into the intake air, the intake improves airflow over the factory airbox, and the Accessport OTS map is calibrated specifically for the Redline CF intake’s airflow signature on the EJ257 platform.

DETAILS

• Includes: Cobb Accessport V3 + Cobb Redline Carbon Fiber Intake
• Platform: 2015-2021 Subaru WRX STI EJ257 MT (inc. Type RA and S209)
• Redline CF Intake: carbon fiber airbox lid, polished aluminum tube, cone filter
• CF lid: lower thermal conductivity — reduced heat soak vs metal/plastic airbox
• OTS maps: 91 octane, 93 octane, E85 — calibrated for Redline CF intake on EJ257
• Accessport live gauges and data logging
• NOTE: Ships via UPS/FedEx — signature required at delivery

Carbon Fiber Thermal Properties on the EJ257 STI Platform

The Redline CF intake’s carbon fiber lid reduces heat transfer from the engine bay into the intake airbox — carbon fiber conducts heat poorly compared to metal or plastic, so less engine bay heat reaches the intake air inside the airbox structure. On a track day or sustained spirited driving where engine bay temperatures rise significantly, this thermal advantage is meaningful: cooler intake air is denser air with more oxygen available per unit volume, which translates to more consistent fuel mixture quality and more consistent combustion from the EJ257’s fuel injection. The Type RA and S209 variants of the 2015-2021 STI are track-oriented from the factory, making the thermal advantage of carbon fiber construction particularly relevant for the driving conditions these cars are built for. Cobb calibrates the OTS map specifically for the Redline CF intake’s airflow signature on the EJ257 — the CF construction produces a slightly different airflow characteristic than the standard SF intake, and the calibration addresses this difference precisely.

CF-Specific Calibration, Gauge Monitoring, and Stage 2 Path

The Accessport’s gauge display provides real-time IAT monitoring alongside boost, AFR, and other EJ257 parameters — directly useful for understanding how the Redline CF intake’s thermal advantage shows up in actual driving conditions. Data logging captures everything at high speed for ProTuner review as the build progresses. The carbon fiber lid is prominently visible when the hood is open, providing the premium engine bay presentation that complements the S209 and Type RA’s factory-hardware builds.

What’s in the Box

• Cobb Accessport V3
• Cobb Redline Carbon Fiber Intake (CF lid, tube, filter, hardware)
• OBD-II cable
• USB cable
• 2 faceplates
• Universal mount

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 Redline CF Stage 1+ package is for STI owners who want the best Stage 1+ intake option available, with the thermal performance benefit of carbon fiber construction validated in the OTS map calibration. For builds heading to NexGen Stage 2, the Redline CF intake carries forward as the intake component — the investment here is not replaced, it becomes part of a larger system.

Fitment

Year	Make	Model	Notes
2015-2021	Subaru	WRX STI	EJ257 MT
2018	Subaru	WRX STI Type RA	EJ257 MT
2019	Subaru	WRX STI S209	EJ257 MT