The Upgrade Guide for NA/NB Miata Headers. One of the best power upgrades for naturally aspirated 1.6L and 1.8L Miatas is headers. Aside from forced induction, you’ll be chasing single-digit horsepower gains with rather expensive mods like headers. As a result, if you intend to install a turbo or supercharger to your NA or NB Miata, I recommend skipping the $400+ headers and instead opting for forced induction.
While we discuss a number of less expensive NA and NB mods in our ultimate Miata mods guide, headers are a must if you want to maximize your naturally aspirated power. That being said, headers not only provide some substantial power gains for NA/NB Miatas, but they also provide a number of additional performance benefits. This post will go through the performance advantages of upgrading the Miata headers, as well as the cost, power improvements, and some of the best headers on the market. This instruction applies to both 1.6L and 1.8L NA and NB Miatas; however, fitting varies by engine and year.
What exactly are Miata Headers?
Headers are merely an extension of the exhaust manifold. When they have been upgraded over the stock exhaust manifold, they are commonly referred to as headers. Headers connect directly to the engine’s exhaust ports and are the initial component of the Miata’s exhaust system.
Exhaust gases escape the engine through the exhaust ports and first enter the headers. The exhaust gas is then routed through the headers to the catalytic converter and ultimately out the tailpipe via the cat-back part of the exhaust. Headers are merely a component of the exhaust system. However, because they are so close to the cylinders, they have a significant impact on power and performance.
Headers are frequently referred to as shorty or long-tube headers. The length of the header piping is referred to here. Catalytic converters are also removed by some long-tube headers. However, headers on the NA and NB Miatas are all the same length. This means that each exhaust port’s piping is the same length. Although aftermarket headers are the same length as OEM headers, the term “equal-length” generally refers to the exhaust port piping. So there’s no need to choose between long-tube and short-tube headers for the Miata.
There are two options for headers: 4-1 or 4-2-1. 4-1 headers merge all four exhaust port pipework into a single pipe. 4-2-1 headers connect two exhaust ports, which are subsequently combined into one pipe. At high rpms, 4-1 headers provide the greatest advantages. 4-2-1 headers have more force throughout the range but less power at the peak than 4-1 headers.
The prevailing consensus for NA and NB Miatas is that 4-1 headers provide the biggest power improvements and performance benefits for racing.
On the Mazda 1.6L and 1.8L, the OEM exhaust manifold and piping are quite long. The catalytic converter is located in the midpipe, which follows the exhaust manifold/headers. As a result, header improvements are not authorized exhaust modifications because they do not remove the catalytic converter. To remove the cats, an aftermarket midpipe will be required.
Performance Advantages of NA/NB Miata Headers
- Gains of 3-5hp (peak hp)
- Gains in torque are comparable.
- Backpressure has been reduced.
- Reduced EGTs
- Exhaust sounds have become slightly louder.
Headers work best when coupled with a complete cat-back exhaust system. The stock NA and NB exhaust is around 1 7/8′′ in diameter, which is narrow and restricted. Replacing this with a 2′′+ system should result in an increase of 3-5hp over the power spectrum. Headers have the largest influence on peak horsepower, which is typically about 6000rpm. The catalytic converters will be retained by using headers and a cat-back exhaust. You should expect roughly 2hp extra if you remove the cats with a race pipe.
One of the most significant advantages of headers is that they lessen backpressure. This reduces exhaust gas temperatures and aids in exhaust gas scavenging. Lowering EGTs and backpressure benefits both performance and engine health.
Sound increases from headers alone are typically negligible. You will notice a deeper tone, but it will not be overly loud. If you’re concerned about noise, headers won’t add much. If you want the best sound, you should also install a cat-back system.
Miata Headers Increased Power
As previously stated, power improvements are concentrated around 6000rpm. As a result, you won’t notice a significant increase in low-end power or torque. The most significant exhaust benefits for the 1.6L and 1.8L Miata come from a cat-back exhaust, which gives gains across the power spectrum. That isn’t to say that headers aren’t worthwhile.
Combining headers and a cat-back exhaust will add 5-8hp, with the lower number representing increases throughout the power range and the larger number representing peak gains. The catalytic converter can be removed for an additional 2hp.
The cost of header and cat-back upgrades is a disadvantage. Headers will cost between $400 and $500, while a cat-back will cost between $400 and $700. So you’re looking at $800+ for only 5-8hp. Turbo kits are expensive, so I appreciate the urge to maximize normally aspirated power, but once all mods are complete, you’ll probably wonder why you didn’t go turbo. As a result, most people think that the best Miata changes are suspension and handling modifications.
Headers for NA/NB Miatas
Because Miata headers are all the same length, there isn’t much difference between them. The metal and finish are the most significant aspects. Ceramic coated headers will outlast others and prevent rust. There are several sub-$200 headers on the market, but they are constructed of cheap metal and rust soon.
Keep in mind that the fitment for NA/NB headers varies by year. Fitment looks like this in general:
- 1990-1993 (NA 1.6L)
- 1994-1997 (NA 1.8L)
- 1999-2000 (NB 1.8L)
- 2001-2005 (NB2 1.8L)
Goodwin Racing has all of your header options available.
1) Miata RoadsterSport Headers
RoadsterSport has the best price-to-quality ratio on the market. Most of their headers are $399, making them the most economical alternative except obtaining cheap ebay headers.
Their headers have a 4-to-1 ratio and are made of 304 stainless steel. The exhaust port part of the tube is 1.5′′ in diameter and widens to 2′′ where they meet. It also includes two bungs for an auxiliary wideband sensor. It also contains a flexible segment of piping that aids in vibration reduction throughout the cat-back portion of the exhaust.
Overall, these are our favorite market headers because they are the most affordable alternative without sacrificing quality.
2) Miata Racing Beat Headers
Racing Beat is most likely the best Miata header. While their headers are slightly more expensive, they use larger 1.7′′ tubing that combines to 2.375′′, both of which are larger than the RoadsterSport option. The one catch is that these do not function with superchargers, so avoid them if you want to install one.
The one disadvantage of Racing Beat is that their headers cost around $550 and are frequently out of stock. They create the headers in small quantities, so they normally don’t have a lot on hand and it can take a while to acquire them. Having said that, they are the largest headers available, which is ideal for lowering backpressure and increasing power.
Related : The Tall Person Mods for NA/NB Miata
3) Jackson Racing / Cobalt
Jackson Racing, which has been operating for a long time, manufactures Cobalt Ceramic Coated headers. Their headers are also made of 304 stainless steel and ceramic coated for long-lasting durability.
These headers are distinct in that they are 4-2-1. The primary tubing measures 1 5/8′′, the secondary tubing measures 1 7/8′′, and the single pipe piece measures 2 3/8′′. This approach distributes power gains across the power spectrum, but gives modest benefits. You’ll see less peak horsepower improvements than with 4-1 headers, but more than 4-1 headers at the low end of the range. Having saying that, these are ranked third on our list since Miata experts agree that 4-1 headers are superior.
Summary of NA/NB Miata Headers
Headers are used to replace the standard exhaust manifold. The factory manifold features a number of kinks and curves that limit exhaust flow and produce backpressure. Upgrading to higher-flowing headers provides a multitude of performance advantages, including minor power improvements.
Finally, in terms of $/hp, headers aren’t the best value. However, if you want to increase NA/NB horsepower without adding forced induction, headers, a cat-back exhaust, and possibly a catless midpipe should be on your mod list. Headers will produce a peak 3-5hp improvement, often around 6000rpm, at the apex of the powerband. They don’t have a lot of power throughout the band, nor do they have a lot of low-end torque.
Because the stock catback on the 1.6L and 1.8L Miatas is also very small and restrictive, headers are best combined with a cat-back exhaust. Replacing the entire exhaust system should yield 5-8hp improvements, with the possibility of adding a few more with a catless or high-flow midpipe.