I had never changed the boots with 210k miles on my 09 F150. My truck was misfiring badly. After changing the plugs and still getting misfires, I looked at the number 8 boot. I bent it and it cracked so I figured these were the culprit of the misfires. This turned out to be the case. No misfires at all now. Don’t wait like I’d did, change them at 100k miles. Change the springs (conductors) as well. I’d say these are every bit as good as OEM. Excellent value. I will get some for the wife’s 012 impala.