Recently i went to a shop and picked up some new Denso Iridiums. i was told to get the Denso Iridium IK22 plug. Im not spraying or boosting and my motor is pretty much stock. I was doing some research online and it said the IK24 plug is the one i should have. Is there any major performance difference if im running a colder plug on a stock motor?

 

a colder plug is for an engine that produces higher temp than a stock engine because of (higher compression, forced induction, etc) so otherwise stick with a stock temp. range plug

 

Im sure Rocket here on H-T can help you out.