The sad truth about some aftermarket performance wires (or waarz, as my uncle Jed calls them) is that a lot of them ain't worth a pee-hole in the snow. Many factory wires have a two-piece connector that grips the spark plug, utilizing both an inner and outer collar. Some after market brands use only one, which means they may not stay on the plug as well as they should. It's easy to check a connector with the naked eye, but it is hard to judge the quality of the insulation or how well the wire will stand up to vibration just by looking at it. In the end, the best advice when shopping for performance replacement wires is to go with tried and true names like Nology, Bosch, and others.