Eric,

You are one stubborn, son-of-a-gun!  This is at least the 2nd time around
for this same discussion and the same conclusions by the more technically
aware list members.

re your:  "What about this theory:  Lower resistance plug cause higher
current flow in coil, more heat and shorts windings internally,
whitch is what I've found wrong."

Same theory, and same analysis and conclusions as before.

One last time.  Secondary coil current is determined by secondary
resistances, including that of the added noise suppression resistance
intended to reduce the amplitude of high frequency harmonics.  I don't
remember the numbers now but it's in the many kilo-ohm range.  Actual
numbers were in the discussion a year or two ago, I think.

But assume 25 kohms total.  Now consider an after-arc, plug resistance from
0 ohm (shorted plug) to 10 ohms, for the sake of discussion  even though I
can't believe the arc through ionized gas would ever be as high as 10 ohms,
no matter which plug.  So, given these assumptions, you have a total
secondary resistance range, during firing, of 25,000 ohms to 25,010 ohms.

Now, do the math and estimate the difference in coil current and then tell
us why you still think this will make or break a coil.  (Pick whatever
voltage you want for open-circuit, secondary voltage.)

//jack