Several Lightnings(5.4L) have had plugs that blew out. Others have found the plugs little more than finger tight.
When you go to change them, remember to not over tighten them as there are only 4 or 5 threads to hold them in the aluminum head. On the Ls, you can't get a torque wrench(13 ft. lbs.) on several plugs so NGK says to tightne them "finger-tight" and then 1/16th of a turn more--careful!
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