NGK 7164 Iridium IX Spark Plugs TR55IX (8 Pack)

The best plugs for Japanese cars

They are great

Fits great works. Great, we'll buy again.

I noticed better performance with these than the stock plugs. So far so good. Great plugs for the price and definitely recommend.

Used for 5.4ll engine. They also can be used for a 4.6l as well. I haven't had any issues with so far.

Work well

Bought these plugs to replace platinum plugs that lasted about thirty thousand miles.I did have to gap all of them to specifications.That is a trivial matter.I bought these plugs because according to my research they are made of the hardest material out there on the market for plugs.I' am expecting at least 70,000 miles before change out,that I can not attest to only time will tell.However I did feel a significant difference in performance. I replaced the plug coils with summit high performance coils because I still had an occasional engine miss fire after replacing the plugs.Since replacing both spark plugs and coils,engine runs smooth,quite, no more engine miss fire,much improved engine performance and improved mileage per gallon.If you replace your plugs and still have engine performance issues,change your spark plug wires and or coils depending on what your engine uses.Replace all of them at the same time not just one or two.These items were replaced on a high performance Crown Victoria engine.GOT IT--GET IT.

Plain copper core is better for the lt1. Iridium core is less conductive.