About the only practical test that an owner can do with common equipment
is to first Ohm test the center conductor,
then re-install the ignition wires,
move the vehicle to the darkest spot you have available,
then (keeping hands safely in clear)
watch the running engine in the dark
for the distinct blue-green color
of 'Corona Discharge'
If there is an electric motor repair shop nearby,
most good shops will have a
'Hi-Pot Tester'
capable of going to at least 4000 volts.
With a Hi-Pot tester
you would connect to the center conductor of the ignition wire,
then dip the middle section of the insulated wire into salt water,
with the ground of the Hi-Pot tester also in the salt water.
Don't submerge either end of the ignition wire where the plugs and exposed metal is.
Good wires will show at least one MegaOhm of insulation integrity.
If you don't want to use salt water (because of the clean up afterward)
you can hand wrap a bare metal wire around the insulated sections for testing, and ground this metal wire for the insulation test.
Magnecor brand are very good ignition wires,
last a long time before breakdown,
but are expensive:
http://www.magnecor.com/magnecor1/truth.htmNGK wires are generally good,
and usually the best wire commonly available.
With the NGK you have to buy two 4 cyl sets for a V8, with the Subaru flat-4 engine wire kits generally having the longest wires.
