I am running Denso IK22 plugs in my 2003 MCS. I used the preset gap when installing them. Mods include 15% pulley, GIAC, intake, exhaust, Nology wires. Have 2% crank pulley to install soon. Car sees "spirited" driving on a regular basis (my commute 5 days a week is up and down Lookout Mountain, Georgia). Any suggestions on how often to change the plugs?

 

i remember mr. webb at webbmotorsports.com saying they should be changed about every 45000miles or so... (something like that)

 

In this post, Ryephile from Detroit Tuned explains why he recommends closer to a 30K mile interval.