Dan,
Short answer: For the street, resistor or non-resistor does not really
matter if you buy a quality plug - unless you have a radio in your car, and
then you may want the resistor plug.
Now for the long answer!
Originally, resistors plugs were made to provide a better idle - an engine
idles better with wide plug gaps, but you could not have wide plug gaps
without resistance in the secondary circuit with the metal used (accelerated
erosion took place at the electrodes). Since the late 1960s and early
1970s, the secondary resistance has been necessary not only to control that
erosion problem, but also to cut down on unwanted "electronic noise" (for
radios , TV, and such). At that time, you could either have non-resistor
plugs with resistor wires, or vice versa. Nowadays, I think all cars come
with both resistor plugs and carbon impregnated string wires. I never use
those wires on LBCs, but 7mm or 8mm silicone insulated wires with solid
metal core.
Modern developments mean spark plugs have progressed from the ubiquitous
nickel alloy tips to platinum or copper- these offer less resistance than
nickel alloy and produce a stronger spark. Also common now are multi tipped
plugs and designs other than the "j-gap" (U groove from DANSO, etc).
I have had good luck with NGK plugs in various cars, including two race cars
(Bugeye and Mazda RX7). I am using NGK BP8ES in the Bugeye.
So. I think the design and material of the plug and its quality are more
important than whether the plug is a resistor or non-resistor type.
JLC
PS: Did you know platinum tipped spark plugs were first developed in England
during WWll for use in fighter planes? I think the Merlin 12 cyl of Spitfire
and Mustang P51 fame
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