Reviewed in Motor Trend several months back, uses a computer designed and ribbed center conducter, ostensibly to give you the fatter spark.
Pregapped at .045. Very smooth idle, looks to be as well made as the NGK's, therefore better made than those Splitfires that were pretty junky when I tried them.
About $4 each so less than Splitfires, lab tests said these were the greatest thing to come out of GM R&D in many years.The #5 plug is the Miata fitment. Economy seems slightly better and performance seems no worse, but then again, I might be driving harder while I'm trying to beat these things up.