Wow, the ignorance! I have done a lot of testing on ign systems....& spark plugs DO make a difference. It may be slight, you may not feel it.....or maybe you will feel it.
[1] I tried the Pulstar plugs in my GTO. Idle was definitely smoother. Had them in for about 6m, when one failed. I went back to NGKs as what I wanted to know was proved.
[2] When the Bosch Super 4 plugs came out, I tried them; they had 4 grd electrodes, & the spark was exposed more directly to the mixture. No, you don't get 4 sparks, but the spark 'selects' which grd electrode it will spark to. The plugs should have a long life because of reduced electrode erosion. As soon as I drove the car, I got surging at about 35-40 mph. Only the plugs were changed. Put the NGKs back in, no surging....
Now what? I have paid for these plugs...
So I cut off 2 grd electrodes.....&...could not
feel any surging. However, I wondered if there still was surging, but I couldn't feel it. So I went back to the NGKs.
[3] A test by D. Vizard that resulted in a large HP loss...from spark plugs.