Introduction: The 300-HP Threshold for the Subaru BRZ

The Subaru BRZ, with its FA20 boxer engine, is a beloved platform for enthusiasts who value balance, handling, and chassis dynamics. However, its factory output of around 200 horsepower at the crank leaves many owners craving more. The 300-horsepower mark is a popular target because it transforms the car into a genuinely quick machine without overwhelming the chassis or drivetrain. Achieving this goal requires careful planning and a significant financial investment.

Two primary paths lead to 300 HP: turbocharging and naturally aspirated (NA) modifications. While the original article provided a basic cost summary, this expanded guide will dive deeper into the component choices, labor implications, reliability trade-offs, and real-world costs you can expect when building a 300-HP FA20 BRZ. We’ll also discuss alternatives like supercharging and budget-saving strategies so you can make an informed decision for your build.

Understanding the FA20 Engine’s Baseline

The Subaru FA20 is a 2.0-liter, naturally aspirated, direct-injection boxer engine. In the BRZ and Scion FR-S, it produces a claimed 200 hp at 7,000 RPM and 151 lb-ft of torque at 6,400 RPM. The engine is designed for high-RPM operation but suffers from torque dip in the mid-range due to the exhaust manifold design and lean factory tuning.

Stock internals include cast pistons and rods, a modest camshaft profile, and a relatively low compression ratio of 12.5:1. The high compression is excellent for NA power but presents a challenge for forced induction — you must reduce the effective compression to avoid detonation. Understanding these constraints is critical before you start spending money.

Option 1: Turbocharging Your BRZ FA20 to 300 HP

Turbocharging is the most straightforward way to achieve 300 HP on the FA20. A well-executed turbo system can produce linear power that surpasses a similarly priced NA build in both peak output and area under the curve. However, the costs add up quickly, and installation complexity is higher.

Turbocharger Kits: The Core Investment

Complete turbo kits for the BRZ range from entry-level to race-proven units. Popular options include the Full-Race Motorsports TwinScroll Kit (around $4,200), the Speed by Spectre (SBS) Gen2 Kit (~$3,800), and the PTE 5858 Kit from FT86 SpeedFactory (approximately $4,500). These kits typically include a turbocharger, manifold, downpipe, wastegate, blow-off valve, oil/coolant lines, and hardware.

Budget kits from less-known brands may cost around $2,800 but often sacrifice fitment, quality, or include inferior turbochargers. Expect to spend $3,000 to $5,000 on a reliable turbo kit alone.

Fuel System Upgrades

The FA20’s direct injection can handle modest boost, but for 300 HP you will likely need auxiliary fueling. A common solution is port injection + flex fuel (e.g., Radium Engineering Auto PCV Catch Can + PI Kit for ~$700). Upgraded fuel pumps, injector spacers, and a hobbs switch for boost-referenced fuel pressure are also required. Budget $800 to $1,200 for a complete fuel system.

Engine Management and Tuning

You cannot run boost on the factory ECU without a tune. Professional tuning from a reputable shop like Visconti Tuning or ECUTek ranges from $600 to $1,200 for a custom calibration. Many tuners recommend an ECUTek ProECU license ($450) plus a base map. For advanced features like flex fuel and boost control, plan for $800–$1,000.

Supporting Modifications

To handle 300 HP reliably, you need a quality intercooler (front-mount, $400–$800), a full exhaust system (catless or high-flow front pipe and catback, $600–$1,200), and upgraded engine oil cooler ($400–$700). A high-capacity radiator ($350–$500) is also wise to control temperatures. Supporting mods add roughly $1,500 to $2,500.

Internal Engine Upgrades: Do You Need Them?

Many budgets skip forged internals for a 300-HP turbo build, but the FA20’s cast pistons are a known weak point. With careful tuning and conservative boost, 300 HP on stock internals is possible, but the margin of safety is thin. For longevity and the ability to push higher later, budget for forged pistons and rods ($1,200–$2,500) plus machining and assembly labor. Many builders skip this initially but regret it when the engine fails.

Labor Costs

Installing a turbo kit is not a weekend job for a novice. Professional installation costs $1,500 to $3,000 depending on the shop and whether internal work is included. DIY installation can save this cost but requires technical skill and specialized tools.

Total Cost Summary for Turbo Route

  • Turbo kit: $3,500 – $5,000
  • Fuel system: $800 – $1,200
  • Tuning: $600 – $1,200
  • Supporting mods (intercooler, exhaust, oil cooler): $1,500 – $2,500
  • Engine internals (optional but recommended): $1,200 – $2,500
  • Labor: $1,500 – $3,000
  • Total range: $9,100 – $15,400

The lower end assumes no internal work and DIY labor; the high end includes forged internals and professional installation. To achieve a safe, reliable 300 HP with room to grow, allocate $11,000 to $13,000.

Pros and Cons of Turbocharging

  • Pros: High power ceiling, strong mid-range torque (once on boost), well-tested platform, many kit options, tunable for high RPM power.
  • Cons: Higher initial cost, heat management is critical, more complex installation, potential reliability concerns if internals are not upgraded, requires careful maintenance.

Option 2: Naturally Aspirated Build to 300 HP

Achieving 300 wheel horsepower (or even 300 crank HP) naturally aspirated on the FA20 is extremely difficult and expensive. Most NA builds stop around 230–240 whp (roughly 270-280 crank) with extensive work. To reach a true 300 HP at the crank, you need a combination of parts that rivals a turbo kit in cost, with significantly less torque.

Intake and Exhaust Systems

A high-flow cold air intake like the Injen SP1630P ($350) and a catless header such as JDL Auto Design EL Header ($700) will free up airflow. You will also need a full exhaust (front pipe and catback) for another $800–$1,400. Combined, spend $900–$1,600.

Camshafts and Valvetrain

Aggressive camshafts are essential for high-RPM NA power. A set of Brian Crower Stage 3 or GSC Power Division S1 cams costs around $1,000–$1,600. You will also need upgraded valve springs and retainers ($400–$600). Total camshaft investment: $1,400–$2,200.

Pistons and Rods

To safely rev higher and handle the increased heat, forged pistons and rods are mandatory for an aggressive NA build. A complete piston/rod set runs $1,500–$2,500. This includes machine work for overbore or cylinder hone if necessary. Expect $2,000–$3,500 with labor for installation.

Cylinder Head Work

To maximize airflow, porting the cylinder head is highly recommended. Professional CNC porting costs $800–$1,500. Combined with new valve guides, seals, and a three-angle valve job, the head work total reaches $1,500–$2,500.

Tuning and ECU

Like turbo, NA builds require custom tuning. An ECUTek tune is common, costing $500–$800. For maximum power, you will also need E85 fuel. A flex fuel kit ($300–$500) and tune for E85 can add 10–15% more power. Budget $800–$1,300 for tuning and flex fuel.

Supporting Mods: Intake Manifold, Throttle Body, Injectors

To reach 300 HP, you may need a larger throttle body (e.g., Kinsler 72mm for $500) and port injection (similar to turbo). A custom intake manifold like ACE Engineered adds $1,200. These are often overkill; many builds cap at 280 crank HP without them. If you aim for 300, budget an additional $1,200–$2,000.

Labor Costs

NA engine builds require significant disassembly. Labor for piston/rod replacement, cam installation, head assembly, and final assembly ranges from $2,000 to $4,000. This does not include tuning or dyno time.

Total Cost Summary for NA Route (Targeting 300 Crank HP)

  • Intake/exhaust: $900 – $1,600
  • Camshafts + valvetrain: $1,400 – $2,200
  • Forged pistons & rods: $2,000 – $3,500
  • Head porting & assembly: $1,500 – $2,500
  • Tuning + flex fuel: $800 – $1,300
  • Optional intake manifold, TB, fuel upgrades: $1,200 – $2,000
  • Labor (engine build & install): $2,500 – $4,000
  • Total range: $10,300 – $17,100

Important reality check: Even with this investment, many NA FA20 builds produce 250–265 whp (approximately 295–310 crank HP) on E85. True 300 whp (around 350 crank) is rare and requires custom cams, ITBs, and extreme head work costing $15,000+. The NA route is rarely the most cost-effective way to hit 300 HP.

Pros and Cons of NA Build

  • Pros: Linear power delivery, simpler cooling, less heat soak, no turbo lag, often better throttle response, high reliability if built correctly.
  • Cons: Extremely expensive per horsepower, low torque output (peak torque often below 200 lb-ft), requires high RPM to make power, limited upside (can’t easily go beyond 300 HP without forced induction).

Other Critical Considerations

E85 Fuel: The Great Equalizer

Both turbo and NA builds gain significantly from E85 ethanol. For turbo, E85 allows higher boost and more timing without knock. For NA, E85 raises the octane ceiling and can add 15–20 hp. Factor in a flex fuel kit ($300–$500) and potentially larger injectors. E85 is the single most cost-effective power adder after the main hardware.

Clutch and Drivetrain

At 300 HP, the stock clutch will slip. Budget $400–$1,000 for a stage 2 or stage 3 clutch kit (e.g., ACT Heavy Duty or Exedy Stage 2). The BRZ’s transmission can handle 300 HP if driven smoothly, but repeated track use or drag launches may break gears. A transmission upgrade is not required initially but be aware of the risk.

Cooling System

Turbo builds generate significant heat. An upgraded radiator, oil cooler, and possibly a dual-pass radiator are essential. NA builds also benefit from better cooling to prevent detonation. Plan $400–$1,000 for cooling upgrades regardless of your path.

Reliability and Maintenance Differences

Turbocharged engines require regular oil changes (synthetic, 3,000–5,000 miles), monitoring of boost leaks, and eventual turbo rebuilds (every 60–80k miles). NA builds, if built with proper clearances and forged internals, can be very reliable and may only need standard maintenance. However, aggressive cams reduce idle quality and low-speed drivability. Neither route is maintenance-free; both demand attention to detail and high-quality lubricants.

Which Route Should You Choose?

The decision comes down to your budget, performance expectations, and willingness to work on the car. If you want a simple, plug-and-play solution that delivers strong torque and easy 300 HP, turbocharging is the clear winner. The total cost is lower for a reliable 300 whp build compared to a maxed-out NA build. If you are willing to invest in forged internals upfront, a turbo car can be very reliable.

If you are a purist who values revving to 8,000 RPM and wants a naturally aspirated power feel, an NA build can be satisfying but you must accept that you will spend approximately the same or more money for significantly less torque. Many enthusiasts start with full bolt-ons and cams, realize NA 300 HP is unrealistic, and eventually move to forced induction. That path wastes money on parts that must be removed or sold.

For a realistic budget of $7,000 to $12,000, a turbocharger kit with modest supporting mods and a good tune will hit 300 whp (approx 350 crank) safely. Do not be tempted by cheap “300 HP turbo kits” that skip essential hardware — they will cost more in repairs.

Before you start, consult with a shop that specializes in FA20 builds. Check forums like FT86Club.com for build diaries, and consider reputable vendors such as FT86 SpeedFactory or Mishimoto for quality parts. ECUTek is the dominant tuning platform; ensure your tuner is certified.

Ultimately, the BRZ FA20 can deliver incredible driving experiences at 300 HP, but it requires a budget that matches your ambition. Choose the path that aligns with your goals, and do not cut corners on safety or tuning. A well-sorted 300-HP BRZ is a joy to drive on both street and track.