We've recently been able to lower the price of these shocks by $180!
The Koni Sport has been around the Miata world for a couple of decades. They are exceptionally long lived with a lifetime warranty for the original purchaser.
We weren't happy with the stock damping for the Sport for the NC due to excessive bottoming, so we worked with Koni to come up with a better setup. These shocks are perfectly matched to FM springs based on our testing. They can also handle significantly stiffer springs as well.
The Sport has adjustable rebound damping.
Also available as a package with Flyin' Miata springs.
Note: The Koni shocks have a 12mm shaft whereas the stock shaft is 10mm. You'll need to drill out the two washers on the upper mount to accommodate this. It's not a difficult task.