I came across this in a research paper:
'Since most automotive engines operate with resistor spark plugs, acceptable ignition of stoichemetric or richer air/fuel mixtures is typically achieved with very low spark energies. As long as the circuit resistance does not increase appreciably, the engines maintain high-performance levels. ' 'For late model engines with ignitions in good condition, the effect of high-power ignition is often small.' IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 25, NO. 2, APRIL 1997
An Efficient, Power Enhanced Ignition System by Gerlad J. Rohwein