They never made an MX5 turbo but as the engine from the mx5 is the same as a 323 you can bolt a turbo or supercharged on them and run 15psi 1 bar straight away with no internal engine mods (apart from fuel intercoolers etc), I have heard you can run even more with the auto engine as they are even lower comp! Hence why there are loads of kits both turbo and supercharged out there.

I had a greddy turbo on mine with a bipes ecu running 12psi with little 14inch wheels and it was the best car I have had to drive. Anymore boost though and the clutch would slip, and the rear diff is only a 6.5inch so my lsd turned into an open diff!