Not 100 percent sure. But on the dyno it was breaking up at high rpms and also the idle is a bit rougher now. So it will not hurt. Once I get them replaced I will see if the idle is better and if the dyno is a little less with the rocky mountains and a bit higher on the horsepower scale. I am going to gap them a bit smaller at .026 with my new favorite tool that I ordered. Then when they wear out a bit they will probably be at about .028. I pulled out two with the help of a friend, one on each cylinder bank. I then put them back as I do not have the new plugs yet nor the tool. I should of taken a picture before putting them back. But I did not.