2022+ Subaru WRX Turbo Shootout: 8 Turbos Tested at the Same Boost

Have you ever wondered which turbo upgrade is actually the best for your 2022+ Subaru WRX? So did we. So we tested EIGHT of them.

Dyno sheets from different shops, different cars and different boost levels only tell you so much. We wanted real answers, so we bolted the factory FA24F turbo and seven of the most popular bolt-on upgrades onto the same WRX, strapped it to the same Dynojet 424x, filled it with the same E60 fuel and tuned every single turbo to hold the exact same boost. One car. One dyno. One variable: the turbo.

Want to skip straight to the data? The full interactive results are at the bottom of the page, where you can compare every turbo at every boost level yourself.

Not Your Average Dyno Day

This was no seat-of-the-pants shootout. Our WRX shop car is wired with more than 12 pressure and temperature sensors from the intake to the exhaust, logged on a MoTeC dash and synced with the COBB Accessport data from every pull. That means we’re not guessing at what each turbo is doing. We’re measuring it: compressor efficiency, pressure ratio, backpressure, turbine drive pressure, intercooler efficiency, intake pressure drop and more. It also let us confirm air-fuel ratio and timing stayed consistent, so no turbo got a better tune than the next.

The contenders: the Blouch 5056XT and 5356XT, Equilibrium EQT-660 and EQT-770, Tomioka Racing VB670, Boost Lab BL54XR and PLM P660, with the factory VB turbo as the baseline. Each one ran flat 14, 16, 18 and 20 psi, then 20 psi climbing to 22, 24, 25 or 26 psi up top, all on a stock engine with torque capped at 415 to 425 lb-ft. Every turbo breathed through the same AMS hardware: our front mount intercooler and intake, plus a few parts you can’t buy yet, including our upcoming catted downpipe, our upcoming turbo inlet pipe with adapters to fit each turbo’s inlet, and a prototype AMS cat-back. More on those soon.

One thing to know before you dig in: this was not a max-power contest. Every turbo ran the same boost targets on a matched tune, with torque capped to protect the stock engine, so we could isolate what each turbo actually does to the engine: backpressure, spool and response. A customer car tuned for maximum safe power would get its own boost curve and timing on each of these turbos, so the peak numbers here aren’t where every turbo tops out. What no tune can change is how hard the engine has to push to get its exhaust out, and how fast the turbo comes up to boost. That’s what this test measures.

Why Backpressure Matters

A turbo is driven by exhaust, so its turbine is always a restriction the engine has to push through. The pressure that stacks up in front of it, shown in the tool as engine ΔP (exhaust manifold pressure minus boost), is one of the clearest measures of how hard a turbo makes the engine work. It shows up three ways:

• Lost power. Every psi of backpressure is work the pistons spend pushing exhaust out instead of turning the crank. On the FA24 that’s about 1.1 hp per psi at 6,000 rpm, before anything else goes wrong.
• Hotter cylinders and more knock. When exhaust pressure outweighs boost, more hot exhaust gas stays trapped in the cylinder for the next cycle. That raises combustion temperatures and makes the engine more prone to knock, so the ECU pulls timing and power drops further, especially on pump gas.
• More heat and stress. Exhaust that can’t get out carries its heat into the exhaust valves, cylinder head and turbo, which is load you don’t want on a stock engine.

The Engine ΔP chart in the tool below shows it clearly. Below about 3,800 rpm every turbo runs negative backpressure, meaning boost outweighs exhaust pressure and the exhaust side is actually helping the engine breathe. Up top, the curves split. At a flat 20 psi and 6,000 rpm, the upgrades ran 7 to 11 psi of backpressure, with the EQT-770 lowest. Ask the factory turbo for 19 psi and it climbs past 20 psi of backpressure while boost fades to 16, roughly double the upgrades and about 22 hp burned just pushing exhaust out.

The Results

Here’s what roughly 180 dyno pulls told us.

• Every upgrade beats stock at the same boost. At 14 psi, every upgrade topped the factory turbo’s 349 whp, making 356 to 371 whp on the same tune. The stock turbine is the bottleneck: at 6,000 rpm the engine fought 11.1 psi of exhaust pressure over boost, versus 4.5 to 8.0 psi with the upgrades, so more of its power went to pushing exhaust instead of turning the wheels. Ask it for 19 psi and it can’t keep up, fading to 16 psi by 6,000 rpm.
• Lowest backpressure: Equilibrium EQT-770. Lowest backpressure and highest turbo efficiency at every boost level, thanks to the biggest compressor in the test and one of the two biggest turbines. That free-flowing exhaust is why it made the most peak power at matched boost from 16 psi up, topping out at 490 whp on 20 → 26 psi.
• Quickest spool: Blouch 5056XT. It hit 90% of target boost at about 2,400 rpm at every flat boost level. At 20 psi, that matches the factory turbo’s 19 psi run almost exactly, making it as close to stock response as an aftermarket turbo got in this test, with the 5356XT next best. The catch is its small compressor: it runs out of breath around 20 psi and topped out at 415 whp, the lowest power ceiling of any upgrade. With the 5356XT spooling right with it at 14 psi and offering far more power on tap, the 5356XT is the better choice for most builds. Cool March test days helped its spool a touch.
• The sweet spot: Equilibrium EQT-660. Second-lowest backpressure and second-highest efficiency at every boost level. It gives up about 270 rpm of spool to the factory turbo at 14 psi, but still reaches full boost before 3,000 rpm and comes in about 300 rpm sooner than the EQT-770.
• Spool versus backpressure is the tradeoff. Bigger turbines let exhaust out more easily but take more energy to spin up: at a flat 20 psi, the EQT-770 was still at 14.2 psi at 3,000 rpm while the rest were near 20. Size isn’t everything, though. The PLM P660’s turbine is about as big, yet it ran more backpressure, so housing and wheel design matter too.
• Matched boost, not max effort. At the same boost, the field ran within about 25 whp at 5,000 rpm, but that’s this controlled test, not a customer tune. Lower backpressure means less knock and more room for timing and boost, so those gaps can grow once each turbo is tuned to its limits.

Spool vs. the Factory Turbo

At 14 psi, the only boost level the factory turbo ran, here’s how quickly each turbo reached 90% of target boost. The Blouch pair basically keeps factory response, the middle four sit about 260 to 330 rpm behind, and the EQT-770 trades the most spool for the lowest backpressure.

Ask for more boost and the gaps grow. From 14 to 20 psi, spool moved 100 to 300 rpm later for every upgrade except the 5056XT, which held at 2,400 rpm, with the EQT-770 losing the most. The factory turbo’s 19 psi reference run also spooled at 2,400 rpm, which puts the middle four roughly 380 to 460 rpm behind stock at 20 psi and the EQT-770 about 770 rpm behind.

Every turbo was tuned to the same boost target and held within about 0.3 psi of it, keeping the whole group within 0.5 psi of each other, which is a big reason it took so many pulls to get boost control dialed in. Warmer inlet air slows spool by about 30 rpm per 10 °F, so the EQT-660, EQT-770 and Boost Lab, which spooled on 89 to 96 °F air, are each a bit quicker than shown. The 5056XT’s cool March air and partly open wastegate roughly cancel out. The tune also ramps its boost target up to full by about 2,350 rpm, so the quickest turbos, the factory unit and the 5056XT, may be even quicker than shown.

All power figures are uncorrected Dynojet wheel horsepower, the shootout’s default. SAE and STD are a click away with its Correction buttons, though those formulas exaggerate weather differences on boosted cars. Runs spanned about 45 to 94 °F, so call a few horsepower a tie. The factory turbo was matched at 14 psi with a 19 psi reference run, the 5056XT ran up to a flat 20, the 5356XT up to 20 → 22 and only the EQT-770 ran 20 → 26.

So, Which Turbo Should You Buy?

• Quick spool for the street: Blouch 5356XT. Spools within about 100 rpm of the factory turbo at 14 psi for near-stock response, but plan on topping out around 450 whp. It matches the 5056XT’s spool at 14 psi with far more power on tap, so there’s no reason to run the smaller Blouch. It also reuses your factory lines, which keeps the install simple.
• Best balance: Equilibrium EQT-660. Second-lowest backpressure in the test with full boost before 3,000 rpm, so it has much more room to grow than the quick-spool options. It’s our pick for E85 and flex fuel builds on the stock engine, where its quicker spool pays off and the engine itself becomes the limit before the turbo does. We expect it to make around 500 whp, on E85, with a stock engine. Equilibrium also ships the best-quality lines of the group.
• Most headroom: Equilibrium EQT-770. A great option if you’re staying on pump gas or plan to build the engine and want to maximize horsepower. With the lowest backpressure and highest efficiency we measured, we think the engine runs better, and safer, on pump gas with the 770, since it’s less prone to knock events. While it made 490 whp in our controlled test, we expect it to be capable of well over that amount with a built engine and supporting modifications, likely 600+, once it’s tuned to its full potential. The trade-off is spool, with full boost arriving around 3,000 to 3,200 rpm.

The right answer depends on how you drive and where you want to take your build, and that’s exactly why we built the tool below.

Dig Into the Data Yourself

The SnailWorks Engineering Team packed every pull into the interactive shootout below. Pick a boost level, toggle turbos on and off, overlay dyno curves and compare spool, backpressure and efficiency head to head. Want to nerd out? The Metrics tab breaks down exactly what every number means and where it comes from.

Want an AMS Turbo for Your WRX?

We’ve measured every turbo in this shootout down to the last psi of backpressure, and we’ve got ideas. Quick spool, big top end and the data to prove it, engineered by the SnailWorks Engineering Team to bolt right onto your VB WRX. If you want us to build the ultimate bolt-in turbo, let us know. Make enough noise and we’ll make it happen.