Three or so months ago I trailered the k24 miata to Dales shop and built a custom 3” stainless steel exhaust. It’s not perfect, but it’s tucked up well, serviceable, and sounds pretty fucking good in my opinion. Some info/detail shots from the build and a finished sound clip below. Oh yeah, The car’s been basically done minus an alignment, RDX injectors, and a tune for a few weeks.
The exhaust has a “full/street” setup with a vibrant muffler and a turn down tip going out the back and then what I guess could be called a “track” setup without a muffler and just a turndown after the rear subframe. I doubt I’ll ever run the track setup, but it takes no time to remove the “axleback” and swap in the little turndown that I can just keep in my toolbox.