RE: Plug gap
look at the plugs under the 2.5. zfr5f-11. the -11 means that these plugs are pre gapped at 1.1mm(.044). NONE of the plugs under the mc column have a -11, plus, there is another brandof spark plugs. then, at the bottom, it gives the gap for these TWO different brands of plugs. so, what it is saying, is for the 2.5, the ONLY plug recommended is the ngk zfr5f-11. for the 2.3, either ngk or denso is recommended, and the gap is .8mm. i think the napa plugs are gold palladium, an alternative precious metals tip. most modern day cars use the 1.1(.044) gap, IF they are normal aspirated. a FORCED INDUCTION motor will always have a smaller gap, because it takes much more voltage to produce a spark when the pressure is higher, which it is in a fi motor. to produce a good spark, it has to either have much higher voltages, or a smaller gap, or both. the cop system on the mc motor gives more positive voltages, and a smaller gap on the plugs insures good combustion. i am continually amazed at people who believe partspersons at napa, pep boys, autozone, yada, yada over what mazda tells you, or what a mazda tech tells you. mazda is concerned that the correct parts are used, so you can keep the car for a long time, and be happy. napa dont give a squat if you can even drive, they just want to sell you parts.