The stock FA20 turbo in the WRX is not a bad unit. It spools quickly, handles daily driving well, and supports a solid power level with the right tune. But once the build starts growing, it becomes the ceiling. For WRX owners researching turbo upgrades, the question is not whether to upgrade, but what to upgrade to.
This guide is for Subaru WRX owners who have already made that decision and want to know which turbo upgrade fits their power goals and build stage.
Why WRX Owners Upgrade the Turbo
The stock FA20 turbo is sized for efficiency and daily drivability. It does that job well. The problem starts when supporting mods, a proper tune, and higher boost push the car past what that unit can flow. At that point the turbo itself limits the power, not the supporting systems around it.
Getting more out of the car means putting in a unit that flows more air at higher boost levels. If you are still weighing whether an upgrade makes sense, the stock turbo vs upgraded turbo guide covers that decision in detail.
What Changes When You Upgrade the Turbo on a WRX
A larger turbo moves more air and supports more power. It also changes how the car delivers that power. Bigger turbos typically spool later in the rev range. The power band shifts compared to the stock unit, and how noticeable that is depends on the specific turbo and how aggressive the upgrade is.
A turbo upgrade also raises the requirements for everything around it. Fueling, tuning, exhaust flow, and engine internals all become more important at higher boost levels. If you are still on stock internals, understanding how much boost is safe on a stock WRX is a useful starting point before committing to a big turbo setup.
Turbo Upgrade Options for the FA20 WRX
The right turbo depends on your power goal, how the car is used, and what the rest of the build can support. There are three general tiers worth understanding.
Street-friendly bolt-on upgrades sit closest to the stock turbo in spool and drivability. These suit WRX owners who want a meaningful power increase without overhauling the entire supporting setup. Power in the 350 to 400whp range is realistic with a proper tune and upgraded fueling.
Mid-range big turbo setups target 450 to 550whp, typically on E85 with upgraded fueling and a reinforced bottom end. Spool is later than a stock replacement, but the top-end power delivery is significantly stronger. This is the most common tier for serious street and occasional track builds.
Top-end competition setups push beyond 600whp. They require large frame turbos, standalone engine management, and a fully built bottom end. The turbo is one piece of a much larger build, and everything else needs to match.
You can compare available options on the turbo upgrades for WRX hub.
Do You Need to Upgrade the Internals First?
It depends on the power level you are targeting. The stock FA20 handles modest turbo upgrades well when the build is properly supported. At a certain point though, the block becomes the weak link. Our post on how much power the stock FA20 can handle covers where that ceiling sits.
For builds targeting 500whp and above, a built short block is the right foundation. Running serious power on stock internals turns an expensive turbo upgrade into an even more expensive engine rebuild. IAG short blocks for WRX and STI are the logical next step for builders pushing past that threshold.
Supporting Mods a Turbo Upgrade Requires
A turbo upgrade does not happen in isolation. Every system that feeds and supports the turbo needs to keep up, or it becomes the new restriction point.
Fueling is the first thing to address. A bigger turbo demands more fuel, and the stock injectors and fuel pump have limits. The fuel pumps vs injectors guide breaks down which upgrade matters more depending on where your build is headed.
A tune is not optional. Running a larger turbo on an outdated tune is one of the most common ways builds go wrong. Our post on what EFI tuning does for your WRX explains why the tune is what actually unlocks the upgrade.
Engine movement increases with torque. Solid engine mounts for WRX and STI keep the drivetrain stable under added load and reduce stress on the block.
The exhaust needs to match the turbo. A bigger unit pushing more air needs a system that flows it out efficiently. Proper WRX exhaust upgrades ensure the gains are not choked off downstream.
Choosing the Right Turbo for Your WRX Build
The best turbo upgrade matches the power goal, the supporting mods already in place, and how the car is actually used. A street build needs a different setup than a dedicated track car. Choosing based on peak power numbers alone, without considering spool and drivability, leads to a build that underperforms where it matters.
Browse the full range of WRX turbo upgrades and find the unit that fits your build and power goals.
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