I went with NGK Iridium Spark Plugs. Very$$ I have no complaint with them of any NGK plug, Execpt for use in my 5hp Mercury outboard. The only plug that could get it to run smooth was the Split Fire. They don't do anything in my Toyota's but they do some thing to small engines that the others can't. I have tried dumping all kinds of oil gas and oil mixes into the 4cycle BS lawn engine and it doesn't foul out.
NGK Iridium Spark Plugs are excellent plugs! They are made from a very hard metal. And wiill last longer than Platnuims.They are rated to last to 90K. Give better throttle response and resist fouling. Require less voltage to spark and deliver increased burn efficiency, spark at leaner air/fuel mixture, produce better gas mileage and higher horsepower. Awesome plug!!