There is onlyone reason to change the plug wires -- dead factory wires. My Miata friends were quite amazed by the fact that my factory wires lasted 80,000km (50,000 miles). The most long-lasting factory wires I've heard of so far have been running 63,000 miles on Richard Lees " '92 Sunburst". If yours can beat that, let me know by email or guestbook. In terms of performance, I didn't find any performance gain in the NGK compares to a healthy set of factory wires.
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with customization