The LS V8 swap is the legendary big-power Miata build, and Flyin' Miata (the "V8 Miata") made it famous. An aluminum GM LS in a ~2,300 lb roadster yields a shockingly light, fast car, but it's a serious, expensive project, not a bolt-on.
Done right, an LS Miata can weigh only a couple hundred pounds more than stock while making two to three times the power
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