I would also look at the Rotrex supercharger from Denmark. Basically a turbine compressor that is shaft driven with a traction drive system. The traction drive results in better performance than a standard centrifical supercharger. Jackson Racing in the states is selling Rotrex supercharger kits. Jackson Racing has a good name for Miata and Honda engine performance products. The Rotrex has been developed beyond the initial stage.
