We tested the factory turbo and seven bolt-on upgrades on the same 2022 WRX, on the same Dynojet. Every chart here compares the turbos at the same boost, so the differences you see come from the turbo — not from one car running more boost than another. Pick a boost level below and explore.
How we tested
- Same car, same parts. A 2022 WRX with the AMS front-mount intercooler, intake, downpipe, J-pipe and cat-back, a COBB Accessport and COBB flex fuel sensor, a Nostrum high-pressure fuel pump and Nostrum injectors, and an upgraded low-side fuel pump. Only the turbo changed.
- AMS turbo inlet pipe. Every turbo ran our soon-to-be-released turbo inlet pipe, which comes with adapters to match different-sized turbo inlets.
- Same fuel. E60 ethanol blend on every run shown.
- Same dyno. A Dynojet 424x chassis dyno, 4th-gear pulls from about 1,500 rpm to redline.
- Same boost. Each turbo was tuned on the COBB Accessport to hold set boost levels: a flat 14, 16, 18 and 20 psi, and 20 psi climbing to 22, 24, 25 or 26 psi at the top.
- Measured, not modelled. Thin-gauge, fast-response thermocouples and high-accuracy pressure sensors before and after the turbo, logged on a MoTeC dash. That data is combined and lined up with the COBB Accessport log of the same run, so we could check that everything else — air-fuel ratio and ignition timing — stayed consistent from turbo to turbo.
- Sensor gaps are marked. The PLM P660's compressor-inlet sensor wasn't reading, so its pressure ratio and turbo system efficiency are left blank rather than guessed (the same for the Boost Lab's 14 psi run).
Compare at the same boost
Boost profile
Turbos in this group — click to hide or show
Boost from full throttle at about 1,500 rpm to redline. The shaded band is the group's typical boost ± 0.5 psi — every run in the group stays close to it. Drag the red handles on the left edge to zoom; double-click for auto.
Horsepower and torque on one axis, the way a dyno sheet draws them: one number scale for both, so every turbo's two curves cross at 5,252 rpm. Hover for each turbo's hp and lb·ft at that rpm. Drag the handles on the left edge to rescale; double-click it for auto.
Open dot: onset, where boost reaches 50% of the ECU's target. Solid dot: spool rpm, 90%. Dashed grey: what the ECU was commanding — the tune ramps its own target up to full by about 2,350 rpm.
Target is the boost the ECU was commanding for the pull, 4,000–5,000 rpm. Intake is the compressor-inlet temperature while it spooled. Flags mark runs whose spool numbers are not like-for-like.
Table at
Column headers sort the table. Every column is defined under .
The turbos published by the maker; measured by AMS
Wheel sizes are inducer / exducer in mm — published by the maker, and measured by AMS where we had the turbo apart. Cover bore is the compressor cover's inducer bore.
What every metric means chart choices and table columns, with where each number comes from
What each number means, where it comes from and how to read it. Flat 20 @ 6,000 is the range across the turbos in the Flat 20 group at 6,000 rpm — a feel for normal. Plot shows it on the Compare chart.