I tried this style of boot and its edges buckled at the valve cover at installation. Perhaps it should be installed with big end to the outside of the valve cover?

Name:  IMG_0902.jpg
Views: 242
Size:  60.1 KB

The OEM boot is shown below, I assume it is still the best boot for sealing the spark plug connectors at the valve cover, right?

Name:  111905449A.jpg
Views: 228
Size:  24.7 KB