I don't know that the coils make any difference, but those and fresh plugs seem to give me a little more pep. No difference in fuel mileage. Picture in prior post is of the original plugs with 33K on them. Guy who was working with me said they were due for changing - but what do I know? I'm not a 100K plug life guy, think 50K is plenty. My big relief is that my engine didn't have the 3 piece plugs that earlier Ford 3V engines have been plagued with. This job ended up taking 20 minutes; I did use anti-seize on new plugs and dielectric grease on the coil boots.