Putting an LS3 V8 engine into the MX5 isn't new. Flying Miata has been doing it for years, starting with the NA, and now has an ND prototype zipping around the US [just like the video below].
This guy did the same thing but he captured the entire build on video. Starting with an NB8B MX5 SE [aka Mazdaspeed]. I'm envious of the car he created at the end. The exhaust sound alone that his MX5 produces is aural porn. That alone nearly sold me on the car.
I wish the laws in Australia weren't so strict, as I'd like to own an LS3 powered MX5. But with our current laws, his car [and the Flying Miata LS3 MX5] is illegal here.
Check out his LS3 V8 Miata Build YouTube Channel to watch the buid. Enjoy.
Here's Episode One of the LS3 V8 Miata Build