I had my mechanic put the Bosch platinum plus 4 spark plugs in my Subaru Forster about 3 years ago. They have been firing just fine with no problems at all noted. I have been told that these plugs can stay in service for quite a number of years without changing them. They come preset so there is no need to gap them. I noticed right away that the engine seemed to respond quicker. As I accelerated I noticed right away that it seemed much smoother. The only catch as I see it on these spark plugs is that they cost more than regular plugs. At the time of purchase about three years ago I paid about 25.00 for them and I thought that to be pretty costly compared to regular plugs. So I could see how some would consider it cost prohibitive. I personally feel since they work so well and last much longer than regular plugs that they are worth the extra money. I will continue to use them as in my opinion they are the best plugs I have ever used. Thumbs up for this winner from Bosch.