The Mazda MX-5 Miata NA (1989-1997) is a lightweight, rear-wheel-drive sports car that has captivated enthusiasts for decades. Its simple, balanced chassis and eager 1.6L or 1.8L engine provide an engaging driving experience out of the box, but many owners soon crave more power for track days, autocross, or spirited back-road driving. Rather than swapping in a different engine or building a custom turbo setup, many turn to purpose-designed performance kits from reputable vendors. This guide reviews three of the most popular forced-induction options: the Vortech supercharger kit, Flyin' Miata’s turbo and supercharger packages, and the Stillen supercharger kit. We compare power output, cost, installation complexity, reliability, and overall value to help you decide which path is right for your NA Miata.

Understanding the NA Miata’s Performance Potential

The NA Miata’s engine, the 1.6L B6ZE(RS) or the later 1.8L BP, is not known for massive power. Stock outputs range from about 115 hp (1.6L in early models) to 133 hp (1.8L in later models). Despite the modest numbers, the car’s low curb weight (around 2,100 lbs) makes every extra horsepower count. Adding a well-matched supercharger or turbocharger can transform the car into a seriously quick machine without sacrificing the nimble handling that makes the Miata famous. However, the stock drivetrain (transmission, differential, clutch) has limits, so performance gains typically require supporting modifications.

The three kits covered here are the most established on the market, each with a distinct philosophy.

Vortech Supercharger Kit

Vortech Engineering is a longtime leader in centrifugal superchargers. Their kit for the NA Miata uses a crank-driven centrifugal compressor that builds boost progressively with engine RPM, offering a linear power delivery reminiscent of a larger naturally aspirated engine. This makes it a favorite among drivers who want predictable, high-RPM power without the sudden surge of a roots-type blower.

Power Output and Boost Levels

The Vortech kit typically adds 90–100 whp (wheel horsepower) when paired with the stock 1.8L engine and proper fuel management. Expect approximately 200–210 whp at around 8 psi of boost. The kit includes a dedicated intake, blow-off valve, and oil feed system. Out-of-the-box settings are conservative, but with an aftermarket ECU and higher boost (10–12 psi), power can reach 230 whp. The centrifugal design produces minimal heat soak compared to positive-displacement superchargers, aiding consistency during repeated pulls.

Kit Contents and Installation

Vortech’s basic kit includes the supercharger head unit, mounting bracket, pulley, belt, and intake piping. A fuel pressure regulator and larger injectors are often included, but you should verify which generation of kit you receive—older kits may require separate fuel management. Professional installation is strongly recommended because the supercharger mounts to a custom bracket that requires precise alignment. Expect a full day of labor. Some cutting of the plastic under-tray is necessary, but otherwise it bolts onto the stock motor mounts.

The kit is CARB-compliant (California Air Resources Board) for 1990–1993 models, which is a huge plus for street-legal use in emissions-testing states.

Pros and Cons

  • Pros: Linear power curve, low heat generation, reliable OEM-like operation, CARB approval available for early NAs, strong mid- to high-RPM pull, relatively quiet under light throttle.
  • Cons: Higher cost (typically $3,500–$4,500 new, installation extra), requires professional install unless you are highly experienced, supporting mods (clutch, exhaust) add to total cost, power delivery is less immediate than a twin-screw or centrifugal blower.

Reliability and Long-Term Ownership

Vortech superchargers are known for longevity. The sealed gear case and self-contained oil supply mean no extra engine oil plumbing. Many owners report over 100,000 miles of trouble-free operation with proper maintenance (checking belt tension, changing supercharger oil every 10,000 miles). However, at higher boost levels the stock Miata transmission becomes a weak point; many owners later upgrade to a Ford 8.8 differential or a stronger five-speed from a later MX-5. Vortech’s limited warranty covers manufacturing defects, but wear items like the belt and bearing are excluded.

Overall, it is a safe, proven option for those who want a reliable, clean-running boosted Miata.

Flyin' Miata Performance Kits

Flyin' Miata is a Colorado-based company that has specialized exclusively in aftermarket parts for Miata since the early 1990s. They offer a wide range of forced induction kits, from budget-friendly turbocharger packages to high-end supercharger and turbo kits. Their approach emphasizes customization and DIY-friendliness, with detailed instructions and community support. Flyin' Miata’s kits often include everything needed for a complete installation, including ECU tuning via a plug-and-play chip or standalone engine management.

Turbocharger Kits: Voodoo, FM-II, and FM-III

Flyin' Miata’s turbo kits are their most popular. The “Voodoo” kit is the entry-level turbo system for the 1.8L engine, using a Garrett T25 turbo at around 8 psi. It includes a custom ECU card (Voodoo box) that overlays fuel and timing adjustments, keeping stock ECU complexity. Power is about 170–180 whp. The FM-II kit steps up to a larger turbo (T3/T4 hybrid) with a standalone ECU (often the Megasquirt PNP), producing 220–240 whp.

The FM-III kit, designed for built engines, can exceed 300 whp and includes a full intercooler, larger injectors, and a programmable ECU.

Supercharger Kits: Coldside and Hotside

Flyin' Miata also offers supercharger options: a “coldside” kit using a Magnuson/Eaton M45 or M62 roots-type blower (mounted on the intake side of the engine) and a “hotside” kit using a Rotrex centrifugal supercharger. The coldside provides instant torque off-idle (popular for autocross) while the Rotrex offers high-RPM power similar to Vortech. Prices range from $2,500 for a basic used setup to over $6,000 for a fully optioned coldside system with intercooler and tuning. Flyin' Miata's kits are known for excellent documentation and customer support, making them a great choice for enthusiasts who want to install the kit themselves.

Installation and Tuning

Most Flyin' Miata kits are designed with the home mechanic in mind. They include detailed step-by-step instructions, pre-wired harnesses, and often a base tune that gets the car running safely. For turbo kits, the included standalone ECU (like the Megasquirt PNP2) allows easy tuning via a laptop. Many owners learn to do their own tuning with help from the Flyin' Miata forums. Professional installation is not required, but it may be preferable for those with limited experience.

Expect a weekend for a turbo install and up to a week for a comprehensive coldside supercharger installation.

Price Range and Value

Flyin' Miata caters to a wide budget: the Voodoo turbo kit starts around $2,000 (plus turbo, intercooler, and tuning), though complete kits run $3,000–$4,500. The FM-II turbo kit is $3,500–$5,500 depending on options. The coldside supercharger kits are $4,000–$6,000. For the money, you get a complete package with professional support. The DIY aspect can save hundreds in labor costs, making Flyin' Miata often the best value for power per dollar.

Reliability and Community

Flyin' Miata kits have been proven over decades of street and track use. Their turbo systems, when tuned properly, are very reliable. The company’s reputation for customer service is excellent, and the active Miata.net forum has thousands of threads about Flyin' Miata installations. The main reliability concern is the Miata’s stock differential; both 1.6L and 1.8L NAs have weak differentials that can fail under aggressive use above 200 whp. Flyin' Miata recommends upgrading to a Torsen diff from a later model or their own beefier unit.

Clutch upgrades are also necessary above 200 whp.

Stillen Supercharger Kit

Stillen (Stillwell Automotive) is a well-known aftermarket performance company that built a supercharger kit for the NA Miata in the late 1990s. While Stillen no longer manufactures new kits for the NA, used kits are common on forums and bring a lower price point. The Stillen kit is a roots-type supercharger (Eaton M45 or M62) that sits on top of the engine like a low-profile blower, feeding the intake manifold via a bypass valve.

Power Output and Driveability

The Stillen supercharger kit provides a boost of 80–100 whp, similar to the Vortech but with an aggressive torque curve from low RPM. Power delivery is punchy off the line, which is fun for street driving. Peak power on a 1.8L engine is around 190–200 whp at 6–8 psi. Because roots blowers generate heat more quickly than centrifugals, intercooling is rare in these kits (some owners add a water-to-air intercooler later). The kit uses a fuel pressure riser and larger injectors, but tuning is limited compared to modern ECU-based systems.

Kit Contents and Installation

A complete Stillen kit includes the supercharger unit with mounting bracket, crank pulley, belt, intake piping, blow-off valve, fuel pressure regulator, and injectors. The kit is relatively self-contained and bolts onto the stock engine without major modifications. However, Stillen kits were designed for pre-1995 cars; later OBD-II NAs (1996–1997) require additional modifications for emissions compliance. Installation is moderately difficult; experienced home mechanics can do it in a weekend. Professional installation runs around $800–$1,200.

Since the kit is no longer sold new, all parts must be sourced used, which means careful inspection is needed.

Pros and Cons of a Used Kit

  • Pros: Low cost (used kits often sell for $1,500–$2,500), strong low-end torque, proven reliability, simple design with few moving parts, large aftermarket support for rebuilds and replacement parts.
  • Cons: No warranty, may require rebuild before installation, tuning limitations (no standalone ECU included; owners must use piggyback or standalone), heat management concerns without intercooler, some parts may be difficult to source (bearings, seals), CARB approval is very old and likely not transferable to newer vehicles.

Long-Term Ownership with Stillen

The Eaton M45/M62 superchargers are durable units that can last many tens of thousands of miles if properly lubricated. The main wear items are the blower’s internal bearings and the coupling to the pulley. Rebuilding a supercharger costs about $200–$400. The supporting fuel system (FMU) can cause lean conditions if not properly adjusted, so an aftermarket ECU is highly recommended for safe tuning. Many owners pair the Stillen kit with a Megasquirt ECU to dial in the fuel and timing curves, which greatly improves reliability.

Overall, the Stillen kit is a budget-friendly option that demands a bit more DIY effort and tuning savvy.

Comparative Analysis

Choosing between Vortech, Flyin' Miata, and Stillen comes down to your priorities: power delivery, budget, installation skill, and long-term plans for your Miata.

Feature Vortech Flyin' Miata Stillen
Power Range (whp) 200–230 170–300+ 190–200
Type Centrifugal supercharger Turbo (various) or supercharger Roots supercharger
New Kit Cost $3,500–$4,500 $2,000–$6,000 N/A (used $1,500–$2,500)
Installation Difficulty High (professional recommended) Moderate to High (DIY possible) Moderate (DIY possible)
Emissions (CARB) Yes (1990–1993) Some kits not CARB; check Older CARB possible but rare
Reliability Excellent Very good (with proper tuning) Good (needs ECU work)
Community Support Good Excellent (Flyin' Miata forums, Miata.net) Good (Miata.net, old forum threads)

Power Delivery

If you want linear, rising power that mimics a larger engine, the Vortech is ideal. It rewards high-RPM driving and is easy to modulate on the street. Flyin' Miata’s turbo kits provide a steeper power spike around 3,500–4,500 RPM, which feels more dramatic but requires more throttle management. The Stillen roots blower gives instant torque from low RPM, making it feel fast in daily driving but less impressive at high RPM compared to the centrifugals.

Cost Considerations

The total cost of ownership goes beyond the kit itself. All three kits need upgraded exhausts (headers, full exhaust) and a stronger clutch. The Vortech and Flyin' Miata turbo systems often require a standalone ECU ($500–$1,000) for best results; the Stillen kit absolutely needs one for safety. Flyin' Miata includes a basic ECU with many of their kits, which lowers the overall price. Vortech and Stillen kits often necessitate aftermarket engine management.

When adding a professional installation, the Vortech and Flyin' Miata kits can cost $5,000–$8,000 fully installed and tuned. Stillen with DIY installation can be done for $2,500–$4,000 total, but with more risk.

Reliability and Supporting Mods

The stock NA Miata drivetrain is fragile above 200 whp. No matter which kit you choose, you should budget for a clutch upgrade (ACT or Exedy stage 1) and a differential swap (Torsen or 7-inch ring and pinion). The transmissions are relatively strong up to 250 whp, but careful shifting is required. Vortech’s lower boost levels (6–8 psi) are kinder to the drivetrain than higher-boost turbo kits. Flyin' Miata’s Voodoo kit (170 whp) is safe with stock drivetrain for moderate driving, but the FM-II (220+ whp) demands upgrades.

Stillen kits at 200 whp are borderline—many owners upgrade to a differential for peace of mind.

Alternatives and Final Thoughts

If none of these three kits fit your needs, consider a turbo kit from Begi (Bell Engineering Group) or a DIY turbo setup using an eBay turbo and a custom manifold. However, the three options above offer the most tested and well-documented paths. For the vast majority of NA Miata owners, Flyin' Miata provides the best balance of price, power, and support. Their extensive guidebooks and helpful phone staff make the process almost painless. Vortech is the best choice for those who want a clean, OEM-like supercharger install with CARB legality and long-term reliability.

Stillen is the budget pick for the mechanically inclined who want a rooty torque rush and are willing to tune carefully.

Before purchasing, check resources like Flyin' Miata’s official site for current kit options, Vortech’s product page for their current Miata kit, and Stillen’s website for any remaining stock. For community feedback, the Miata.net forum’s Power Modifications section is invaluable. Also, consider reading MiataTurbo.net for detailed build threads.

Conclusion

Each of these performance kits can turn your NA Miata into a thrilling machine. The Vortech supercharger offers high-RPM horsepower with unmatched reliability and CARB approval for early NAs. Flyin' Miata’s turbo and supercharger kits provide the most versatility, from a mild 170 whp to a wild 300 whp, with excellent support for home installation. The Stillen supercharger is a budget-friendly option that delivers low-end torque and a classic roots feel, though it requires more tuning effort. Your choice depends on your budget, mechanical skill, and driving style.

No matter which path you take, you’ll end up with a more powerful and even more enjoyable Miata that will put a smile on your face for years to come.