Now i have heard quite the story of these from different people. the tops are diamond shape to the spark shoots toward instead to the side. now horsepower tv and American muscle have both tried these on their here shows and Both have said great things (prob just getting paid to say it) now from the Big V8'ers out there i have heard they dont change anything at all and as a research many agree. but as i continued my search more rice burners (four bangers) have see a little And i MEAN LITTLE MPG raise and little more power. ( <--- thats BS motors are so small the sparks pushing ) I just wanna know what some opions are on this subject and if anyone has tried them