So my Evo started sputtering a little at wot in higher rpm. I took out the plugs and they were pretty white on the ends and they were the esix plugs. I'm thinking about putting in the bpr7es plugs. Would this cause any problems and what is the advantage of using a $15 each iridium plug?

 

Should be no problems. Copper is an extremely good conductor but lasts nowhere near as long as iridium. Change them every 6 months to a year. Some do it every oil change but it depends on what the car is used for and the type of fuel and mods. Be sure to gap around .22 to .24. Gaping iridium is possible but can easily be messed up if done incorrectly.

 

My spark plug wires look kind of white on bottoms and cyl 4 is like burnt brownish color. Think that could be part of the sputtering problem?