Calibration and performance library
Understand calibration methods, upgrade paths, fuel strategies, emissions constraints, and supporting hardware used in modern performance tuning.
Essential reading
Begin with the broad references, then continue into the subject sections below.
Compare a Subaru WRX e-tune with an in-person dyno tune by process, safety, cost, power, drivability, and fit for VA, VB, and STI builds.
01
Compare remote, dyno, and open-source calibration paths.
Compare a Subaru WRX e-tune with an in-person dyno tune by process, safety, cost, power, drivability, and fit for VA, VB, and STI builds.
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Learn how a Subaru WRX e-tune works, including base maps, Accessport datalogs, map revisions, required equipment, completion time, and safety.
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Learn how a Subaru WRX dyno tune works, from the pre-tune inspection and baseline pull through ECU changes, validation, cost, and the final dyno graph.
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Learn how open tuning works on the VA and VB Subaru WRX, including Atlas, compatible cables, ECU flashing, datalogging, COBB differences, and safety limits.
Read guide02
Understand modification stages and the software or emissions rules that affect available hardware.
Learn what WRX Stage 1, Stage 1+, Stage 2, Stage 2+, and Stage 3 mean after COBB Project Green Speed, including VA, VB, STI, CVT, and custom-tune differences.
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Cobb Project Green Speed changed WRX tuning, downpipe support, DTC deletes, flex fuel, and Stage 2 packages. Here is what still works in 2026.
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Fuel-system strategies and supporting hardware for calibrated performance builds.
WRX flex fuel is back through COBB CAN Flex Fuel for supported VA and VB WRXs. Here is what changed after Green Speed, which kits fit, and what to verify before running ethanol.
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If your Subaru WRX, WRX STI, Forester XT, or other turbocharged model is tuned and you have a Cobb AccessPort, you probably monitor some parameters related to knock, or at least have heard that you should. While many owners are worried when they see any knock, this isn't always a concern. In this article, we'll explain how Subaru's knock control system works, and how the various parameters are related.
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