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Supported Vehicles:

  • Model year 2008-2014 STI (North American, ADM Spec)

*To confirm your model year, you can refer to the tenth value in the VIN number on the vehicle. For model year 2001-2009, the 10th value in the VIN will be the last digit of the model year. For model year 2010-2019, the 10th value in the VIN will be A-K, starting with 2010, ending with 2019.

Current Map Revision:







NexGen Stage2 1050X
(USDM Only)


NexGen Stage2 1050x + Flex
(USDM Only)


Accessport Firmware: 

  • AP3-SUB-003: or greater

  • AP3-AU-SUB-003: or greater

Fuel Requirements:

Each map lists the minimum required octane. A higher octane fuel can be used safely on a map designed for lower octane. DO NOT use maps designed for higher octane with lower octane fuels. Top Tier gasoline should be used where available.

  • Maps designated with "93" are for use with 93 octane fuel (98 RON) or better.

  • Maps designated with "91" are for use with 91 octane fuel (95 RON) or better.

  • Maps designated with “ACN91” are for use with 91 octane fuel found in Arizona, California, and Nevada or better.

These maps are designed for E10 fuel (fuel with 10% ethanol content). For those who only have access to E0 fuel (fuel with 0% ethanol) it is recommended to use the "91" octane version of the maps and datalog the car to ensure your fuel is performing to the necessary level. This is especially important for those using Canadian 94 octane E0 fuel. 

Stage 1 & 2

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Hard Parts Configuration

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C.A.R.B Note

The above calibrations (Stage1, Stage1+FF, NexGen Stage2 1050x) are legal for use on Emissions Controlled Vehicles in all 50 states when used in accordance with the manufacturer's application guide because it and the parts have a California Air Resources Board (CARB) Executive Order (EO) number: 

  • D-660-16

  • D-660-17

  • D-660-99

For additional information on CARB EO availability or the actual letter. Please check out our page CARB EO numbers for COBB Subaru Products

NexGen Stage2+Flex Fuel

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NexGen Stage2+FF Gains

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NexGen Stage2+Flex Fuel

  • Intake Requirements:

    • COBB SF Intake+Airbox 715300

    • COBB Turbo Inlet 712450

    • COBB Throttle Body Coupler 712455

  • Exhaust Requirements:

    • Stock Downpipe

    • Catback Exhaust

      • Factory Cat-Back

      • COBB Stainless Catback 515122

      • COBB Titanium Catback 515140

  • Subaru Spark Plugs 2018 Type RA/2019+ STI spec. D44700

  • Fuel System Upgrades

    • COBB NexGen Flex Fuel Kit (2 parts) 315260, 315670

    • COBB Fuel Pressure Sensor Kit 315650

    • COBB 1050x Injectors 312150

    • COBB Billet Fuel Rails 343150

    • COBB Fuel Line Kit 343250

    • COBB Fuel Pressure Regulator Kit 315250

    • AEM In-Tank Fuel Pump 315450

  • Boost Targets

    • 91 Octane 95 RON Minimum: ~19.0psi ACN91 (Arizona California Nevada 91Octane): ~18psi peak boost pressure tapering down as you approach the 6900RPM redline, +/- 1.5psi.

    • 93 91 Octane 98 95 RON Minimum: ~19.0psi  ~19psi peak boost pressure tapering down as you approach the 6900RPM redline, +/- 1.5psi.

    • E85: ~20psi 93 Octane 98 RON Minimum: ~19psi peak boost pressure tapering down as you approact 6900RPM Redline approach the redline, +/- 1.5psi.

Non-Performance Maps

Economy Mode, Intake+Economy Mode

  • Boost Targets: Typically around 6psi - 12psi

  • Rev Limiter: 5800 RPM

  • ACN 91 or better fuel

Anti-Theft Mode

  • Will not allow vehicle to start

Valet Mode, Intake Valet Mode

  • Boost Targets: Typically around 6psi - 12psi

  • Rev Limiter: 3200-3800 RPM

  • ACN 91 or better fuel

Monitoring Boost Levels: 

The best way to determine if you are hitting target boost is to watch the TD Boost Error parameter. This parameter is your target boost (including altitude and temperature compensations) minus your actual boost (negative values mean you are over the target by the amount while positive values mean you are under). Ideally you want this value to be between 0 and 1.0 at wide open throttle (WOT), but -1.0 to 1.0 is acceptable assuming that you don’t have any significant knock corrections. Overboosting is more likely to occur in higher gears and with colder outside temperatures, so be sure to verify boost levels during these conditions.

High Altitude: 

A quick note for those of you that live at higher altitudes. It is common for turbocharged cars at higher altitudes to run less boost pressure due to lower air pressure and air density. Your turbocharger has to work harder to compress a less dense air mass compared to the same turbocharger at sea level. This must be factored in when determining if your turbocharger is running the proper amount of boost pressure and not being pushed beyond its efficiency range. 

Example: If you live in Denver at 5280 ft and are trying to run a peak boost pressure of 15 psi, your turbocharger has to work the equivalent of making ~17.5 psi at sea level.

There are barometric compensations within the factory ECU that lower boost targets as you climb in altitude in an effort to keep the turbocharger in its optimal range. The COBB performance maps utilize these compensations and therefore, it is perfectly normal for the final boost target to be lower than what is listed for your map. 

Boost Select: 

All maps designated with “Boost Select” in the map name have a driver-controlled boost target controlled through the SI-Drive system available on the 2008+ STI. From the factory, SI-Drive will modify throttle settings and change the relation between what is done with the accelerator pedal and how the throttle blade reacts; [S#] being the most aggressive throttle settings, [S] being less aggressive, and [I] being very conservative.  What we have done is take that functionality a step further.  The “Boost Select” maps have selectable boost targets by toggling between [S#], [S], and [I].  [S#] will target the highest boost level, [S] will be a medium boost level, and [I] will be the lowest boost level (wastegate spring pressure) with conservative throttle mapping.  You can find the specific boost targets for [S#], [S], and [I] in the Map Version Notes above.

Revision Notes: 

titleClick To Expand:

Version #



NexGen Stage2 1050x+Flex Map Release


New NexGen Stage2 1050x maps for USDM Vehicles


Maps updated to eliminate unnecessary DTC Supression or updated versions for parity with other maps/vehicles within the platform


Maps have been updated to eliminate unnecessary DTC suppression.


  • Revised Engine Load Compensation tables to address potentially high absolute values in the A/F Learning "C" range.

  • Activated new toggle to induce Per-Gear Timing Compensations for 6th gear.

  • Eliminated factory "Fuel Enrichment Ramping" behavior that caused temporarily lean conditions following shifts while driving aggressively.


  • Reverted idle speed tables to factory defaults to alleviate high idle speed on certain model years with v330.

  • Revised WGDC tables to address underboosting concerns with v330.

  • Adjusted Primary Ignition Accel. values for smoother transition from Cruise table values.

  • Reverted "I" Mode to use stock throttle mapping values.

  • Adjusted "S" and "S#" modes to be more responsive.

  • Revised AVCS mapping.


  • Added full support for the Cosworth Panel Filter.

  • Slight adjustments made to the AVCS tables for better spool and MPG (minor).

  • Adjusted factory logic to keep the boost control system disabled when DAM is below a certain value.

  • Uses more aggressive wastegate duty cycle reduction below 50 degrees F to help with colder weather over boosting.

  • Reduced boost target reduction at high intake air temperatures when using AEM and SF Intake to alleviate a low boost condition when ingesting hot air from the radiator fans.

  • Alleviates some of the “dead” pedal feel on initial take-off.

  • Revises per-cylinder timing to use most timing on cylinder nearest to the knock sensor.

  • Another batch of updates to help reduce the 2800 RPM stumble present on these cars from the factory.


  • Added full support for the USDM 2013 STI.

  • "I" Mode is now programmed to allow for wide-open throttle operation at the mechanical minimum boost level. The factory logic to automatic switch to "S" Mode when driving aggressively in "I" Mode is no longer enabled. Additionally, "I" Mode and "S" Mode have been altered to provide the same throttle response as "S#" Mode, just at varying boost levels.

  • Additional adjustments made to the AVCS and Manifold Pressure Compensation tables to help reduce the “2800 RPM stumble” phenomenon.

  • Minor revisions made to primary fueling, ignition, and WGDC tables.

  • Boost Target and WGDC Compensations revised to provide safer operation at high elevations.

  • Thorough overhaul of factory Per-Gear Timing Strategy to now gradually decrease overall timing as gear and load go up (the factory logic did the opposite).


Minor revisions for 2012 model year. Includes minor “vehicle usability” improvements such as an increase to the Cruise Control Maximum MPH Limit.


(2008 – 2010 STI only) Incorporates “Boost Select” feature to enable driver-activated secondary boost target via SI-Drive mode selector switch (S mode is lower boost, S# mode is higher boost). Includes improvements to ignition timing, primary open loop fueling and knock learning ranges.


  • Now compatible with Launch Control and Flat-Foot Shifting (LC/FFS) features (MT only).

  • These maps have been created with the newly-released Accesstuner Pro Maps created with this version of Accesstuner software require the latest Accessport firmware (version or greater) be installed. All Accessports must first be updated before using maps created with this latest Accesstuner version. Accessport Manager 2.0 will automatically update the Accessport to the latest firmware version and is available for download on the COBB Tuning Support web page.


Fueling strategies have been made more consistent to help eliminate the 2800-3200 RPM stumble reported by some and to help with more consistent fueling, modified ignition advance settings for improved fuel economy, modified individual cylinder ignition trims, and created LWG maps for those experiencing over boost conditions.


Improved S# throttle response. Addressed reports of over boost issues under heavy loads.


Revised Boost Limits parameters, modified wastegate duty cycles (WGDC) tables to avoid boost creep in higher gears, and increased authority for the boost control system to make corrective adjustments.


Original Mapping. Adjusted Fuel, Ignition Advance, Boost Control, Camshaft Phasing (AVCS), closed loop control, knock corrections, throttle mapping, and base programming logic. Revised Closed Loop management (REFLASH MAP CHANGE) for improved driving quality. Smoothed out boost related values, improved boost response at lower RPM. Modified the fuel metering calculations for more accurate fueling calculations for the specific fuel.