Brian,
Have you heard of any exhausts for the MX5 yet? I'll be picking up my MX sometime in the next two weeks, shortly thereafter I'll be working with a friend of mine to develop an exhaust since the market in new and a little slow moving.
If nothing is available we'll probably be working on a single exit stainless & Ti exhaust that may involve the removing of the black dual exhaust shroud. It'll save the weight Mazda should have, and add a little zing&bling.
If the market doesn't move quickly I'll be keeping this board updated on my progress.