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Greddy Supreme SP Exhaust Review - 2016+ Mazda MX-5 Miata

Greddy is known for its quality parts performance parts. They represent the highest standards in automotive aftermarket parts. Since the ND was released we have been waiting to see what they had in store. Well it's here and we are proud to be one of the first in the USA to install, review, AND dyno test the Greddy Supreme SP for the ND Miata! 

Design and Installation

Greddy has always impressed us with their quality and attention to detail. This exhaust is no different. The welds are the work of an artisan. Materials are high quality and the whole exhaust is built to last. Every part of the exhaust is polished to a mirror finish. The tips beautifully are etched with the the Greddy logo, for a subtle, yet proud stamp of Greddy quality.

greddy supreme sp miata 2016 nd

The Greddy Supreme SP comes in two flavors, the Axleback Exhaust and the Full Exhaust. The Axleback exhaust is the piece shown below. It is a direct replacement for the OEM axleback system. This version is great for those who want to personalize the sound of their ND without affecting the emissions components. Some states are more strict than others when it comes to this topic. 

greddy supreme sp exhaust miata nd 2016

The Full Exhaust variant, which is the one we are reviewing today, includes two additional pipes (shown below). It replaces all of the OEM piping after the header and removes the secondary catalytic converter. In its place you get a series of two resonator units. This exhaust not only gives you a more aggressive exhaust note, but Greddy estimates that there is a +10HP gain. More on that later!

Installation was extremely easy. Fitment was perfect so everything went it as expected. The hardest part was probably battling with the rubber exhaust hangers!


Around town and at low rpms, it's not much louder than stock but gives a satisfying grumble. At wide open throttle it opens up to a deep, sporty exhaust note. Greddy did an excellent job tuning the sound. Exactly what you'd expect out of a Greddy! Don't take our word for it though. Check out the vid.

Performance and Dyno results

We dyno'ed the car prior to install, and after the installation, we needed to allow the car to relearn its fuel and timing settings in order for it to take full advantage of the added airflow. We took it out for a spin and did some cruising as well as some pulls onto the freeway. At first there did not seem to be much difference, but as we drove it more we got a little excited. It seemed to pick up quicker around the lower and middle range. We couldn't really tell up top. After a few more sets of pulls and some cruising, we decided it was time to take some measurements on our trusty Dynomite Hub dyno!

Well were there gains? We are happy to say, YES! Our butt dyno did not lie! The car gained torque across the board with a max gain of about 13ft-lb in a couple areas. It also gained HP across the board with the majority of gains being in the mid range from about 3500 to redline. Max HP gain seemed to be around 9 horsepower. Pretty decent results for just a bolt on exhaust!

What it didn't help however is the torque drop off from about 4500 to redline. It gained torque through that range but it still slopes down at a steady rate. We suspect that this is because of the high velocity small diameter intake ports of this particular motor.

Product Links:

Greddy Supreme SP Full Exhaust 2016 Miata ND

Greddy Supreme SP Axleback Exhaust 2016 Miata ND

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