Aboothman, thanks for agreeing with me and showing the problems with Crystal's torque plate assumptions.
Now I will explain why torque plates are not needed for gaping the rings.
aboothman calculated .0015" as the max circumfrence difference so I will use that number.
Ring gaps are measured with a feeler gauge (thickness gauge), which is a go/no go gauge. Feeler gauges come in .001" increments and do not measure the gap. The user can only tell if the gauge fits or does not fit. i.e. a .015" gauge fits too loose, a .016" gauge fits ok, and a .017" gauge does not fit. For this example, that means the gap is greater then .015" and less then .017". Only by feel can one determine how close the gap is to .016". So with practice one can get closer to feeling what he believes is .016" but it is not exact.
So now when a max circumference difference of .0015" is used the most the ring gap will be off is one feeler gauge. If it is not the max the difference will be between a tight .016" and a loose .016". If we were building F1 engines, this would matter. But for 99% of the Subaru engines built here by members, the difference will not matter.
Just because a process is more complicated does not make it right.