Both are emission type ultra long life (100K) plugs that require a perfect A/F and a new car cylinder/ring pack to last as they dont usually have the beans to burn themselves clean. In a 'dirty A/F' carb app, they wont last. I like the NGK V-power with the split "forked tongue" ground. On the other hand, EFI does make for a clean combustion but paying >$9 for a plug is insane for a V8 (how about a 2 plug per jug hemi?) who's plugs are right there to take out and test or clean or replace or change heat ranges.
