A package of 16 straight 3D-printed spark plug wire looms in gray.
Two each 2-wire, 3-wire and 4-wire looms.
Paint them your wire or engine color or chrome/stainless steel.
They accept Pro Techs's Spark Plug Wire, or if you want soft draping spark plug wires, check here (black only - see photo above). You may have to drill one or more holes for the wire to fit.
3D-printed, by Greg's Scale Model Accessories, 1/25 scale.