I have some Magnacore plug wires which work great, however the plug hole covers are worthless. After a little heat they shrivel up to nothing. So, I made some covers using some ducting metal from Home Depot and heavy duty felt for placing under furniture. I cut the metal in a pi shape after measuring the diameter of the plug boot and the plug opening, using tin snips. Next, cut the felt to match leaving a slice to install over the wire. The felt is self adhering and sticks right on the metal. Just snug it up to the engine tin.

I've been driving around for a few weeks and they stay put. I was concerned the felt might not hold up from the heat, but it has not been effected. Thought I would pass this along to help keep your engine cool.