Well, I'm speaking from experience. My car kept throwing misfire codes for all cyl. When I went back to stock plugs those codes went away. Several mechanics I've talked to told me that the bosch plugs don't work well in japanese cars. I don't know what the reasoning behind that is, but maybe it's because you can't adjust the gap on those plugs. If you really want to get better plugs, go with the denso irridium plugs. They are expensive, but are suppose to be good. I'm not sure but our stock plugs might already be platinum or irridium. I can guarantee you tho, you will not see any performance gains.