MAKING IT FASTER
Previous generation Miatas were among the most receptive cars in this market when it came to making changes that improved their driving character. Their B6 and BP engines were filled with strong forged parts that loved boost. Their chassis were fundamentally good and parts were readily available. The new MX-5 shall remain tuning friendly. Here's why:
Mazda's 2.0- and 2.3-liter engine blocks are, for all practical purposes, perfectly interchangeable. The 2.3 is 12.5mm taller, but all the engine and accessory mounting bosses are the same--even between the front- and rear-wheel-drive versions.
Common sense tells us the head from the 2.0-liter mill is better (it's the reason the 2.0 currently makes more power than the 2.3) and it bolts to the 2.3-liter block.
Mazda's 2.3-liter engines are currently available in the Mazda3 and Mazda6, the upcoming Mazda5 as well as the Tribute. Or you can source one from Ford's Escape, Focus or Ranger.
The front cover from the MX-5's 2.0 is different than the current 2.3, so you'll need the updated cover from the '06 Mazda6 (probably with its front engine mount removed). You'll also need the 2.3's longer timing chain and probably some tensioner bits. A custom header is also in order as the stock manifold will hit the firewall on the taller 2.3. The MX-5's crank pulley will be necessary to keep the belts turning and its flywheel is lighter--you'll need both of those.