I am not done yet with replacing the spark plugs & installing the new Thunderbolt 50 plug wires, due to the spark plug mix-up, but there are a couple items worth noting:
1. The original plugs I pulled, at 2 years & 8,500 miles, looked great. They could have been left in with no performance issues at all. They also looked exactly the same. This next set will go 3 years.
2. The original plug wires are nylon wire tied to the frame, and I have not given them a through inspection, but where they were tied, they were too tight & cut the outer insulation.
The new wires are so much better quality, it won't be a issue, plus I will install them properly.
I did wiring bundle installations on F18's at McDonnell Douglas & you use a manual gun to tighten & cut those nylon tie wraps & if the gun is not set properly, you can damage cables.
The stock spark plug cables are also very flimsy IMO.