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The Flame Thrower 40,000V coils have internal resistance rated at 1.5 or 3.0 ohms.
Flame Thrower II coils have lower resistance at 0.6 ohms.
Flame-Thrower III coils have extremely low resistance of 0.32 ohms.

Yes that's true that you need to know what coils you're dealing with. I didn't think about factoring the aftermarkets like pertronix and the very low resistance coils. I was thinking oem point style coils from 50's to 70. I myself am running a Pertronix 40011 as a 6 volt positive ground rated at 1.5 ohm. I think that one also comes in a 3 ohm rating.