ive used them on my 2001 jeep grand cherokee with the stait 6 4.0 and my mileage went up from 16 to 18 mpg it had 175000 miles on it. my question is has anyone used them on the 2009 to 12 hemis. and noticed anything?
I know 2 people that tried them in the 4th gen Hemi (an 09 and a 10). In both cases they ran into issues within a week and ended up replacing them with the plain old ordinary OEM copper plugs and haven't looked back.
Don't understand why, but the Hemi just doesn't seem to like exotic plugs. :4-dontknow: