Upgrading Your Brz Fa24: Cost-effective Ways to Add 40 Hp

The Subaru BRZ FA24 Platform: Unlocking Affordable Horsepower

Since its debut, the Subaru BRZ with the FA24 engine has earned a reputation as one of the most engaging sports cars under $30,000. The 2.4-liter flat-four, producing 228 horsepower from the factory, offers a stout foundation for tuning. Enthusiasts quickly discovered that the FA24 responds well to modifications, often delivering more power per dollar than many turbocharged rivals. Adding 40 wheel-horsepower (whp) to your BRZ is not only possible—it’s realistic with a carefully chosen set of upgrades that won’t break the bank.

This guide breaks down the most cost-effective ways to reach that 40-horsepower goal, covering bolt-on parts, calibration, and supporting modifications. We’ll also examine dyno-proven combinations, budget ranges, and reliability considerations so you can build a faster, more responsive BRZ without sacrificing daily drivability.

Understanding the FA24’s Tuning Potential

The FA24 engine shares its architecture with the WRX’s FA24F, but the BRZ version uses a high-compression (12.5:1) naturally aspirated setup. Factory tuning leaves significant room for improvement, especially in mid-range torque and top-end power. The main bottlenecks are restrictive intake and exhaust components, conservative ignition timing, and a lean air-fuel ratio designed for emissions. By addressing these areas, you can safely liberate 40–50 whp without touching internal engine components.

Key advantages of the FA24 platform include a robust block, forged connecting rods (in the 2022+ BRZ), and an efficient dual VVT system. These features allow for responsive tuning with minimal risk, provided you stick to high-octane fuel (91–93 AKI) and monitor knock correction.

Cost-Effective Upgrades: The 40-HP Recipe

Below are the most impactful modifications, ranked by horsepower-per-dollar. Many owners combine two or three of these upgrades to reach the 40 whp target. We’ve included typical price ranges and real-world dyno results from community testing.

1. MAF-Adapting Cold Air Intake (5–10 whp)

A quality cold air intake (CAI) improves airflow into the FA24, reducing restriction and lowering intake air temperatures. Systems like the GrimmSpeed CAI or the Perrin intake are designed to maintain proper MAF scaling, which is critical for consistent fuel trims. Expect 5–10 whp gains, mostly in the mid-range, with a noticeable induction sound.

Cost: $300–$450
Installation difficulty: Easy (1 hour)
Dyno result: +7 whp / +5 lb-ft (Perrin, 93 octane)

2. Cat-Back Exhaust (3–8 whp)

A cat-back exhaust system reduces back pressure and can add 3–8 whp, depending on pipe diameter and muffler design. For the BRZ, systems like the Borla S-Type or MagnaFlow Street offer a good balance of flow and sound. Keep in mind that a cat-back alone won’t yield huge gains—it shines when paired with an intake.

Cost: $600–$1,200
Installation difficulty: Moderate (2 hours)
Dyno result: +5 whp (Borla S-Type)

3. ECU Tune (15–20 whp)

An ECU tune is the single most effective upgrade for FA24 BRZs. By recalibrating the fuel maps, ignition timing, and throttle response, a tune can add 15–20 whp with no hardware changes. Popular options include OpenFlash Tablet (OFT) and Ecutek (professional custom tune). OFT users report consistent 16–18 whp gains on 93 octane, while a custom dyno tune can push 20+ whp safely.

Cost: $300–$600 (OFT), $500–$900 (custom Ecutek)
Installation difficulty: Easy (plug-and-play with tablet)
Dyno result: +18 whp / +15 lb-ft (OFT Stage 1, 93 octane)

4. Front Pipe Upgrade (3–6 whp)

The OEM front pipe (the section between the header and catalytic converter) is somewhat restrictive. Replacing it with a high-flow or catless front pipe can add 3–6 whp and improve spool (for torque). Many aftermarket cat-back systems include an optional front pipe upgrade. Brand like Manners Racing offer front pipes with or without a catalyst.

Cost: $200–$400
Installation difficulty: Moderate (2–3 hours)
Dyno result: +4 whp combined with cat-back

5. Lightweight Flywheel (Gains in acceleration, not peak HP)

While a lightweight flywheel (approx. 11–13 lbs vs. stock 19 lbs) does not increase peak horsepower, it reduces rotational inertia, improving throttle response and acceleration. The car feels quicker and more eager to rev, which translates to a more enjoyable driving experience. Combined with other mods, the flywheel helps deliver the power more effectively.

Cost: $400–$700
Installation difficulty: High (requires transmission removal)
Performance: 0.2–0.3 sec quicker 0–60 (estimated)

6. Performance Spark Plugs (Minor gain, reliability upgrade)

Upgraded spark plugs with a one-step colder heat range (e.g., NGK LFR7AIX) are often recommended when adding a tune and bolt-ons. They help prevent pre-ignition under higher cylinder pressures. While peak horsepower gain is minimal (2–5 whp), they provide insurance for aggressive tuning.

Cost: $60–$120
Installation difficulty: Moderate (30 minutes)
Benefit: Reduced risk of knock

Combining Upgrades: The 40 WHP Sweet Spot

To achieve a verified 40 whp increase on a 2022+ BRZ FA24, the community has settled on a proven combo: cold air intake + cat-back exhaust + ECU tune. This package typically nets 30–35 whp on 93 octane, leaving room for a front pipe or header swap to reach 40 whp. A sample build:

• GrimmSpeed cold air intake (+7 whp)
• Perrin cat-back exhaust (+5 whp)
• OpenFlash Tablet Stage 1 tune (+18 whp)
• Manners Racing front pipe (+4 whp)
• Total: +34 whp (easily reach 40 whp with a custom tune or a header)

For those on a budget, skip the front pipe and instead invest in a custom Ecutek tune. A skilled tuner can extract 20–22 whp from a tuned car with intake and exhaust, bringing the total to 32–37 whp. Add a header (see below) to push past 40 whp.

Optional: Headers for Bigger Gains

Unequal-length headers are popular for the classic Subaru rumble, but equal-length designs produce better top-end power. Brands like Tomei and Gruppe-S offer EL headers that can add 10–15 whp when combined with a tune. However, headers increase cost and installation complexity. For strictly 40 hp on a budget, start with intake + exhaust + tune.

Real-World Dyno Data

We compiled data from multiple BRZ owners on forums like FT86Club and GRB Forum. The following table summarizes average wheel horsepower gains (on a Mustang Dyno) for common combinations:

Modification Set	Average WHP Gain	Estimated Cost
Intake only	+7	$350
Intake + exhaust tune	+25	$1,100
Intake + exhaust + tune	+32	$1,450
Intake + exhaust + tune + front pipe	+36	$1,750
Intake + exhaust + tune + header	+45	$2,500

As shown, reaching 40 whp is best achieved by adding a front pipe or header to the basic intake/exhaust/tune package. The total investment ranges from $1,750 to $2,500—a fraction of the cost of forced induction.

Budget Planning and Prioritization

Creating a structured upgrade path helps you stick to a budget and avoid wasted money. Here’s a recommended order:

1. ECU tune first — gives the biggest single gain for the lowest cost. Drive with the tune for a few weeks to feel the difference.
2. Cold air intake — complements the tune and adds induction sound. Reinstalling the stock tune for intake is not required if you have a reflash or tablet.
3. Cat-back exhaust — enhances sound and frees up top-end power. If budget is tight, start with a used exhaust or a simple axle-back.
4. Front pipe or header — pushes you past 40 whp. This is the point where a custom tune becomes more valuable than an off-the-shelf map.
5. Lightweight flywheel & spark plugs — optional supporting mods that improve drivability and reliability.

Sample budget breakdown for a 40 whp build:

• Used OFT tablet: $350
• GrimmSpeed intake: $380
• Used cat-back (Perrin or Invidia): $500
• Manners front pipe (used): $200
• Total: $1,430 — can reach ~36 whp. Add $200 for a custom e-tune to hit 40+ whp.

If you prefer all new parts, expect to spend $1,800–$2,200.

Reliability Considerations

Adding 40 whp to a naturally aspirated FA24 is well within safe margins. The engine’s forged internals (2022+ models) and high-compression design handle moderate power increases without issue. However, keep these points in mind:

• Always use top-tier 93 octane (or 91 if 93 is unavailable). Lower octane can cause knock, especially with aggressive tunes.
• Monitor your oil temperature. Track days or hard mountain driving may require an oil cooler (about $400).
• Install a catch can or AOS to reduce carbon buildup on the intake valves, a known DI engine issue.
• Have your tune checked on a wideband dyno to ensure safe air-fuel ratios (12.5–13.0 under load).
• Replace spark plugs every 30,000 miles if running a tune and aggressive driving.

With proper maintenance, a 40 whp BRZ remains reliable for daily driving and occasional autocross.

Frequently Asked Questions

Can I get 40 whp from a tune alone?

No. Off-the-shelf tunes for the FA24 BRZ typically give 15–20 whp. To reach 40 whp, you need bolt-on hardware that improves airflow. The tune unlocks the full potential of those parts.

Do I need a flex fuel kit?

E85 can add 15–20 whp on top of a pump-gas setup, but it requires a flex fuel sensor, injectors (maybe), and a custom tune. It’s effective but more expensive (~$800+). For a simple 40 hp goal, stick with 93 octane.

Will these mods void my warranty?

In the US, a dealer may deny warranty claims for parts that caused the failure. An ECU tune is often detected via flash counter. If warranty is a concern, use a reflashable tablet and reflash to stock before dealer visits. Intake and exhaust are reversible.

What headers are best for NA power?

Equal-length headers (e.g., Tomei EL, Gruppe-S, ACE) provide the best top-end gains. Unequal-length headers produce a rumble but sacrifice 3–5 whp in the high RPM. For pure power, choose EL.

Final Thoughts

Adding 40 horsepower to your Subaru BRZ FA24 is an achievable goal with a clear path: start with a tune, add an intake and exhaust, then finish with a front pipe or header. The total investment of $1,500–$2,500 delivers a significant increase in driving excitement—transforming the BRZ from lively to genuinely quick. Focus on quality parts from reputable manufacturers, use a proper tune, and maintain your car diligently. The result is a well-rounded, reliable track-day weapon that still shines on the daily commute.

For those who want to push beyond 40 whp, the FA24 responds well to E85, lightened drivetrain parts, and even centrifugal superchargers (300+ whp). But for the budget-conscious enthusiast, the bolt-on plus tune formula remains the smartest way to extract meaningful power without breaking the bank—or the engine.