does this make scence at all??

you're right about the optimum air/fuel for power is 12.7:1 (for best burn 14.7:1, and for fuel economy 17 or 18:1) and it sounds like you'll be able to achieve this. I personally would never mess around with heat ranges because you could easily melt a plug especially with that high voltage ignition, but if you strictly plan on racing it, then i'd swap it. i know that when you change ignition systems the actual power comes from increasing the gap, so you should be fine there, but you're getting into tricky territory with the heat ranges. Another thing to think about is that the larger gap you get the more you stress the coil, so it may fail eventually. Good luck, keep us posted!

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'84 Mustang 5.0 T5, FMS aluminum radiator & 180* thermostat, 1 5/8 shortys/2.5" duals, '88 GT tail lights and wheels, Holley 4160 4 BBL, smog pump idler, more coming soon