Buyer Guide: 2004-2005 Mazdaspeed MX-5 Miata

A Natural Fit

Adding a hair dryer to the Miata wasn’t as much of a stretch as it sounds. The car’s iron-block four-cylinder hails from the brand’s B-series engine family, and factory-turbocharged versions had already been used in the Mazda 323 GTX and Mercury Capri XR2. And, of course, thousands of enthusiasts had already shown that the Miata could reliably handle boost. 

At first glance, the Mazdaspeed Miata’s engine bay looks as if it were designed to accommodate a turbocharger from the get-go. The ducting, for example, fits perfectly. 

Parts were chosen with an eye to compact size and good street performance. A smallish IHI turbo with a ball-bearing center section provides the necessary 8.5 psi of boost–enough to raise horsepower from 142 to 178.

Unique 17-inch Racing Hart wheels are the easiest way to identify a Mazdaspeed MX-5, but the special badges and little intercooler in the grille will also tip you off.

The turbo Miata was dubbed the Mazdaspeed after the company’s in-house tuning arm. It wasn’t the first car to be so named, though, as the 2003 Mazdaspeed Protegé held that honor in the U.S. market. Subtle Mazdaspeed badges hinted that the car was something special next to ordinary Miatas.

The Mazdaspeed Miata featured a number of other improvements over the non-turbo Miata LS, including Bilstein dampers, shorter and stiffer springs sourced from the previously optional Sport suspension, and 17-inch Racing Hart wheels. It came standard with the LS’s optional six-speed manual transmission and a limited-slip differential.

Down in Flames

The Mazdaspeed Miata bowed to positive reviews. It could do zero to 60 in less than 7 seconds–about a second faster than an ordinary NB Miata. And the best part? The boosted Mazda didn’t lose any of the midrange flexibility and throttle response that made the car so appealing in the first place. It was like a Miata, only more so.

The biggest downside to the new car was availability: Mazda announced plans to produce only 4000 of the cars per year, although this turned out to be optimistic. Despite the bargain-basement price of less than $26,000, few left dealer lots. While all the 2004 models eventually sold, a fire in the production factory late in 2004 sealed the fate of the Mazdaspeed after just more than 1400 units were shipped for the 2005 model year. That means only about 5400 cars were shipped our way. 

The car doesn’t lose any of its character when fitted with a turbo. Inside, you’ll find all the interior goodness of an LS-trim car. 

It’s difficult to see why the Mazdaspeed Miata didn’t fare better. The minimal increase in cost (only around $700 more than a Miata LS) was far less than an aftermarket turbo kit, and the car came with a full factory warranty and dealer support. Even if the buyer planned to upgrade the engine later, it was a great place to start.

Nearly 10 years on, the Mazdaspeed Miata is more than a historical curiosity–it’s one of the finest examples of the original Miata platform and an astonishing driver’s car with enough power to be entertaining. Thanks to the turbo powerplant, a little tuning goes a long way, too, making the Mazdaspeed Miata an attractive alternative to far newer cars.

Things to Know

The hardest part about buying a Mazdaspeed Miata is simply finding one. With only 5428 cars built across two model years, they aren’t exactly growing on trees. Assuming you find an example in a color you can live with–there are only four options, so don’t get too choosy–current book values are between $6000 and $10,000. In our experience, there aren’t many cars in the lower end of the range. Asking prices are generally near $10,000 and higher. 

Engine and Drivetrain

The Mazdapeed Miata hasn’t been plagued by many problems, but the most common one is the dreaded “bog” caused by a faulty three-way MAP solenoid. When the solenoid fails–usually after a long freeway drive–the car will buck and refuse to accelerate smoothly. Normally a check engine light will accompany the problem. 

A second common problem is a failing fuel pump that won’t allow the car to start. The least expensive replacement comes from Walbro: Figure around $100 compared to $400 for the factory piece. 

The factory intake and downpipe are both extremely restrictive, so replacing both with aftermarket parts adds a quick power boost and more consistent performance. (Here’s a hint: Check out the Flyin’ Miata website if you’re considering buying one of these cars. When paired with their Mazdaspeed exhaust, the company claims that the car makes an extra 23 horsepower and 26 ft.-lbs. of torque, thanks to their downpipe and catalytic converter.)

Installing a larger exhaust will pay off in faster turbo spool times–3 inches is usually the largest that can be fitted practically. 

Once you’ve upgraded the intake and exhaust, the intercooler can become a power limiter. The factory intercooler is rather small, and larger, aftermarket replacements help in some situations. (We should note, however, that they may not pay off in increased power with the stock turbo.) 

The boost can be raised slightly via a manual or electronic boost controller, although the factory ECU is not happy above 10 psi or so. The injectors will run out of steam before that point and will have to be replaced. This, of course, will require some sort of piggyback ECU to manage the higher flow rates. 

With all the tricks, the factory turbo can flow enough air to top 200 horsepower. Flyin’ Miata offers a bolt-on package that pumps up the Mazdaspeed to 225 horsepower at the wheels. The contents include an intake, throttle body inlet pipe, blow-off valve, downpipe, midpipe, exhaust, intercooler, Hydra Nemesis ECU and 700cc injectors. They offer additional Mazdaspeed Miata packages as well.

To make big power–above 250 ponies at the wheels–you’ll need to replace the factory turbo. Flyin’ Miata offers several turbo replacements that swap the factory IHI snail for a Garrett unit with much more headroom than the stock turbo. Now you can probe the limits of the engine’s bottom end–figure results of more than 300 horsepower. 

The Rest

The rest of the Mazdaspeed Miata is standard-issue Miata, meaning few problems exist. At the same time, the aftermarket is ready to deliver all sorts of suspension and brake upgrades.