EJ257 — CONFIGURATOR v2.6

Build Your
Engine Package

2.5L / 150.3 CID99.5mm BOREREV B — 2026.02BOXER PERFORMANCE
TURBO
FMIC
FUEL
TBE
ECU
EJ257 — 2.5L FLAT-FOUR
Tap a component to configure
ACT.I
Act One — Baseline

Stock EJ257.
237 wheel horsepower.

This is where every build starts. The curve plateaus at 5,200 RPM. Torque falls off a cliff past 4,800. The boost controller is hunting. You feel it every time you merge.

DYNO CHART — STOCK BASELINE
2022 WRX CVT · 93 OCT · 68°F
WHP
TQ
3002752502252002k3k4k5k6k7kRPM
Peak WHP
237
Peak TQ
241 lb-ft
Peak Boost
14.2 psi
AFR
11.8:1
EXHAUST AUDIO — STOCK
Full throttle pull · 3rd gear
0:000:12
TUNER NOTES — BASELINE PULL
[01]Boost controller hunting 14.2 → 12.8 psi under load
[02]Power curve flattens at 5,200 RPM — stock ECU cut
[03]AFR goes rich (10.9:1) past 5,500 — safety pull
[04]Charge temps +42°F over ambient at peak boost
Scroll to build
ACT.II
Act Two — The Build

Parts go on.
Numbers go up.

CURRENT BUILD — WHEEL HP
237whp
DYNO CURVE — LIVE BUILD
3003504003k4k5k6k7kSTOCK
GAIN vs STOCK
+0 whp
STEP 01 — TBE

Turbo-Back Exhaust

Cobb SF Intake + Tomei Expreme Ti. Charge temps drop 8°F. Exhaust flow up 34%.

STEP 02 — FMIC

Front Mount Intercooler

Perrin 600x300 core. Charge temps now within 8°F of ambient. Boost holds flat.

STEP 03 — FUEL

ID1050x Injectors

Fuel system headroom unlocked. Now safe to push boost past 18 psi.

STEP 04 — TURBO

Garrett GTX3076R

Ball bearing CHRA. Full boost by 3,200 RPM. Curve climbs to 7,200.

STEP 05 — ECU

Full Custom ECU Map

12 dyno pulls. Boost curve razor-flat. Knock-safe 93 oct. 412 whp on the Mustang.

RESULT
412 wheel horsepower.
On a stock EJ257 block. 93 octane. Street-driven daily.
ACT.III
Act Three — Results

Cars we've built.
Numbers that don't lie.

Marcus T.'s 2018 WRX — 398 whp build by Boxer Performance
Marcus T. · Portland, OR
2018 WRX
WHP
398
TQ
374 lb-ft
BOOST
21 psi

"Boxer built my car twice — once when I blew the stock turbo, and once when I decided to actually do it right. 398 whp on a stock block. Daily driver."

GTX3071RFMICTBEID1050xECU
Kenji R.'s 2021 STI S209 — 441 whp build by Boxer Performance
Gridlife MIDSOUTH — T3 Class
Kenji R. · Seattle, WA
2021 STI S209
WHP
441
TQ
410 lb-ft
BOOST
22 psi

"Gridlife MIDSOUTH T3 class. Boxer did the tune on E85. 441 whp. Car pulls to 7,400 like it's angry."

GTX3582RFMICTBEID1300xFull Flex E85
Priya N.'s 2022 BRZ — 312 whp build by Boxer Performance
Priya N. · San Jose, CA
2022 BRZ
WHP
312
TQ
290 lb-ft
BOOST
18 psi
Forced Induction KitFMICECUTBE
Devon W.'s 2019 WRX STI — 415 whp build by Boxer Performance
GTA — High Plains Raceway
Devon W. · Denver, CO
2019 WRX STI
WHP
415
TQ
388 lb-ft
BOOST
22 psi
GTX3076RFMICTBEID1050xFuel PumpECU
340+
Builds Completed
+187
Avg WHP Gain
12–18
Dyno Pulls / Week
441 whp
Stock Block Record
Book a Dyno Baseline

Start with the truth.
We'll show you what's possible.

Send us your year, model, and current mod list. We'll schedule your baseline pull and send back a written build plan with target numbers and itemized pricing within 24 hours.

DYNO BASELINE REQUEST — FORM v1.4
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