These leads are made at our UK HQ. Ford Mustang 8mm Double Silicone HT Leads. Suitable For: The classic Ford Mustang 289 or 302 V8 engine. Highest-Quality Blue Silicone HT Lead Set - UK-Made. Our HT leads use double silicone insulation surrounding a carbon ferroflex core for maximum electrical suppression and spark transfer, and minimal interference and power loss.