When I worked aftermarket auto parts unless a customer absolutely, specifically, requested Champions I wouldn't sell them except as a last resort. Not only do Champions wear quicker but they foul easier than ANY plug I have ever seen. They do not recover from getting gas soaked very well either.
Many HEMI owners who have installed CAI kits have found that the initial rich condition caused by the computer when it senses all the cold air, and before it adjusts to the new air flow, fouls the plugs to the point they need replacing. Most plugs will take some rich conditions to some extent but not Champions. Get them the least bit wet and they won't recover.
If they provide such a good spark they should be able to handle a little extra gas but they can't. Champions are the absolute WORST plug out there. One of the mechanics at the dealer I use, a young pup still wet behind the ears, gave me the same speech about them when I mentioned I was going to change my plugs out long before the 30K. I just politely stopped him and told him I had been a MOPAR guy all my life, and a parts guy for years and years, so save it. Not buying it. When he began shaving regularly he could lecture me on plugs
Champion = CRAP! Shame on DC for using them in the HEMI when they already use NGK in a lot of their other vehicles.