I have both a 2000 S2000 and a 2006 MX-5 and the trunk shapes don't look like it would be a bolt on without doing some modifications. But the widths of the trunks are about the same. As mentioned above. It looks like you could just adjust the mating surface on the bottom of the spoiler. It probably would not take much to make it work. And here is a spoiler thats not exactly the same as the one you posted but its close.

http://www.good-win-racing.com/Mazda...t/61-0658.html