PCMforless LT1 performance spark plug wires offer an easy way to change to over the valve cover style routing. These wires are already manufactured to correct length, numbered, and ready for install. Offered with and without Spark Plug Wire Loom Kit. Add the PCMforless heat/fire sleeves for the ultimate protection! The 7mm and 10.4mm wires are largely the same with the exception of an extra outer fire sleeve and larger looms to accomendate the larger wires.