The Subaru FA20 engine is the heart of three iconic sports cars: the Subaru BRZ, the Toyota 86 (formerly Scion FR‑S), and the Toyota GR86 (second generation, which uses a larger FA24 engine — but this article focuses on the original FA20‑powered models). While the engine and chassis are essentially identical across the three brands, subtle differences in factory calibration, intake plumbing, and exhaust routing can affect how modifications translate into real‑world power. This article examines the power gains from common modifications applied to the FA20 in both the Subaru and Toyota platforms, backed by dyno data and owner experiences.

Whether you’re building a dedicated track car or just want a peppier daily driver, understanding these differences helps you pick the right parts for your specific car. We’ll cover everything from simple bolt‑ons to full forced‑induction setups, and highlight why two cars that share the same engine can still show slightly different results on the same dyno.

Stock Performance Baseline

Before diving into modifications, it’s important to establish the stock power figures for both cars. The FA20D (naturally aspirated) produces 200–205 horsepower at the crank and 151 lb‑ft of torque. On a typical Dynojet, most stock FA20‑powered BRZ and 86 models put down 170–175 wheel horsepower (whp) and 140–145 lb‑ft of torque at the wheels. The torque curve is famously flat, with a dip between 3,000 and 4,500 RPM — a common target for aftermarket improvements.

Factory ECU Differences

From the factory, the Subaru BRZ and Toyota 86 (and the early Scion FR‑S) run different ECU calibrations. The Toyota calibration tends to be slightly more conservative on ignition timing at low RPM and uses a different throttle map. The Subaru calibration runs slightly richer mixtures in some regions. On a dyno, stock BRZ and 86 often show nearly identical peak numbers, but the curves can diverge in the mid‑range. After a tune, these differences all but disappear because aftermarket ROM files overwrite the factory quirks. Still, if you run only a cold air intake without a tune, the factory ECU differences might cause the two cars to respond slightly differently — the Toyota may adapt more aggressively to increased airflow.

Cold Air Intake (CAI)

Cold air intakes are one of the first modifications enthusiasts choose. They replace the restrictive factory airbox and resonator with a larger, smoother intake tube and a high‑flow filter. For the FA20, most CAIs pull air from the front bumper area or behind the headlight.

Subaru BRZ CAI Gains

Popular options for the BRZ include the Perrin Cold Air Intake and the Injen Short Ram Intake. On a stock tune, a CAI on the BRZ typically adds 5–10 whp and a small improvement in throttle response. Some owners report losing a bit of low‑end torque due to the removal of the factory intake resonator, but the mid‑range and top‑end gains are measurable.

Toyota 86 CAI Gains

The Toyota 86 uses a slightly different airbox design and intake duct. The duct has a different cross‑section and the resonator shape varies. Aftermarket intakes designed specifically for the 86 often fit the BRZ as well, but the factory airbox differences mean that the gains can be 1–2 whp different between the two cars. In practical terms, both see the same 5–10 whp gain. Because the ECU is not re‑tuned, the main benefit is sound — the intake noise becomes more pronounced.

Cat‑Back Exhaust System

A cat‑back exhaust replaces the piping from the catalytic converter back to the muffler. It mainly affects sound and reduces backpressure, but on a naturally aspirated FA20, the gains are modest without other intake mods or a tune.

BRZ vs 86 Cat‑Back Gains

Both cars respond nearly identically to a cat‑back. Gains are 8–12 whp at the top end, with little change to peak torque. The Subaru BRZ uses a slightly different mounting bracket for the mid‑pipe, but aftermarket cat‑backs are interchangeable. The Toyota 86 sometimes benefits from a slightly better resonator design in aftermarket systems because the factory unit is more restrictive. Overall, a cat‑back is more about sound and weight reduction than pure power.

Header (Exhaust Manifold) Upgrade

The stock FA20 header is an unequal‑length design (EL is aftermarket; stock is actually equal‑length on the FA20? Let me clarify: The FA20 in BRZ/86 uses an equal‑length header from the factory. Wait, earlier FA20 in Subaru models like the WRX uses unequal? Actually, the BRZ/86 FA20 has a tubular equal‑length header as standard. That’s correct — it’s a four‑into‑two‑into‑one design with equal-length primaries. So why do people upgrade? Because the factory header is still very restrictive with small primary tubes and poor collector design. Aftermarket headers (e.g., Tomei Unequal Length, P&L Equal Length, or Gruppe‑S) often use larger primaries and merge collectors that improve flow.

For the FA20, a good aftermarket header is the single best power‑per‑dollar modification. Gains of 15–20 whp and 10–15 lb‑ft of torque are common, and the infamous torque dip around 3,500–4,500 RPM is mostly eliminated. Both the BRZ and the 86 respond equally to the same header. The installation is identical because the engine block and exhaust flange design are the same. Some headers require a tune to fully maximize gains and avoid check engine lights, but even without a tune, the seat‑of‑the‑pants improvement is noticeable.

ECU Tune / Remap

Aftermarket tuning is where the FA20 truly wakes up. The most common tools are the COBB Accessport (using off‑the‑shelf maps or custom tunes) and ECUtek (often used by professional tuners). A stage 1 tune (on a stock car except for maybe a cat‑back) typically yields 15–20 whp and a much improved torque curve — the torque dip is significantly reduced. A stage 2 tune (intake + header + tune) can push gains to 30–40 whp over stock.
The factory ECU differences between Subaru and Toyota become irrelevant once a tune is applied because the tuner works with the same ROM parameters. However, the 86’s stock ECU might have slightly more aggressive timing in certain rev ranges, so the percentage gain from a tune can be a bit less on the Toyota. In practice, the final numbers are within 2–3 whp of each other.

Forced Induction: Supercharger & Turbo

For those chasing serious power, forced induction transforms the FA20. Kits are available from Edelbrock (supercharger), Harrop (supercharger), GReddy (turbo), and HKS (turbo). Power gains depend on boost level and supporting mods, but typical numbers are 80–120 whp over stock at medium boost (~8–10 psi). With a built engine and higher boost, 300–350 whp is achievable on a stock bottom end (with a conservative tune).

Both the BRZ and 86 handle forced induction identically from the engine perspective. The only differences may come from the cooling system: the Subaru BRZ has a slightly different oil cooler location and the Toyota 86 has a different radiator shroud, but aftermarket kits accommodate both. A supercharger kit will produce the same horsepower on either chassis. The limiting factor is the transmission — the stock six‑speed manual is fragile around 300 whp, and both cars use the same transmission, so upgrade options are the same.

Flex‑Fuel / E85 Tune

Switching to ethanol‑blended E85 allows the engine to run more ignition timing and higher compression pressure because of ethanol’s higher octane and cooling effect. On a naturally aspirated FA20 with a tune, E85 can add 20–25 whp over 91‑octane pump gas. The gains come from aggressive timing maps and a richer fuel mixture. Both cars require an ethanol content sensor and a tune (COBB or ECUtek). The power gain is virtually identical between the Subaru and Toyota platforms, though the Toyota’s lower‑octane stock tune might see a slightly larger percentage increase. Supporting mods (like larger fuel injectors) are not needed for NA, but for boosted setups, injectors and a fuel pump may be required.

Full Bolt‑On Comparison

To summarize the typical cumulative gains, consider a stage 2+ setup: cold air intake + cat‑back + header + tune + E85 on a naturally aspirated FA20.

  • Intake: +5–10 whp
  • Cat‑Back: +8–12 whp
  • Header: +15–20 whp
  • Tune: +15–20 whp (on top of bolt‑ons; total stage 2 ~35–40 whp)
  • E85: +20–25 whp

Total: roughly 60–80 whp over stock, bringing wheel horsepower to around 230–255 whp. Both the Subaru BRZ and Toyota 86 achieve these numbers with the same parts. The only variability comes from dyno corrections, ambient temperature, and the specific tune. There is no inherent advantage for either brand in terms of bolt‑on power.

Reliability and Supporting Mods

As power increases, reliability becomes a concern. The FA20 is a well‑engineered engine, but it has known weaknesses:

  • Direct injection carbon buildup – no fuel wash over intake valves. Periodic walnut blasting or catch cans help.
  • Oil starvation – under high lateral G on track, stock oil pan can starve the pickup. A baffled oil pan or oil cooler is recommended for track use.
  • Valve spring failure – early 2013 models had a recall; later models are fine.

For forced induction, upgrading the fuel system (injectors, pump) and installing an oil cooler are mandatory. Both cars share the same maintenance schedule and aftermarket support, so no brand has a reliability advantage.

Real‑World Dyno Results

Across numerous FT86Club and NASIOC threads, owners report that a 2013 Subaru BRZ with Perrin intake, Perrin cat‑back, and a stage 2 COBB tune puts down 205–215 whp on 93 octane. A 2014 Toyota 86 with the same parts yields 203–213 whp. The difference is well within dyno variance. With a header and tune (often called “stage 2³”), both cars crack 220 whp. The first brand‑specific comparison dyno test conducted by FT86Club users showed the Subaru holding a 2‑whp advantage, likely due to a slight difference in intake temperature from the factory duct. However, swapping the intake equalizes everything.

Cost‑Effective Power Recommendations

If you’re on a budget and want the most power per dollar, here’s the order of mods for both Subaru BRZ and Toyota 86:

  1. ECU Tune (COBB Accessport or ECUtek) – $600–$900, +15–20 whp.
  2. Header (Tomei, P&L, or others) – $400–$700, +15–20 whp (requires tune to maximize).
  3. Cat‑Back Exhaust – $600–$1,200, +8–10 whp. (Better sound is a bonus.)
  4. E85 Flex‑Fuel Kit + Tune – $300–$600, +20–25 whp (if E85 available in your area).
  5. Forced Induction Kit – $4,000–$7,000, +80–120 whp.

These recommendations apply equally to the Subaru and Toyota versions. The parts are interchangeable, and aftermarket companies rarely differentiate between the two brands except for brackets or hoses that have minor variations.

Conclusion

After analyzing dyno sheets, owner reviews, and tuner data, it’s clear that the Subaru FA20 engine in the BRZ and the Toyota 86 behaves nearly identically when modified. Any reported differences are within the margin of dyno error or stem from slight factory calibration variances that a tune completely erases. The most significant power gains come from a header and tune combination, while forced induction offers the ultimate increase for those willing to invest.

Whether you own a Subaru BRZ or a Toyota 86, you can follow the same build path and expect the same results. Focus on quality parts, a proper tune, and supporting mods for reliability. Your choice of badge should be based on personal preference for styling, interior, or brand loyalty — not on power gain potential, because under the skin, they are the same car.

For further reading, check the COBB Tuning website for official dyno charts, and the FT86Club forums for thousands of build threads with real dyno results.