If you follow the simple wiring diagram it doesn't require you to replace the wiring but it is an opportune time to upgrade to some fresh wiring of an upgraded gauge.I went so far as to wrap and route the power feed wires through the radiator core support with the other regulator wires to keep it as inconspicuous as possible. I went ahead and upgraded the actual headlamp harness and new sockets to head off any wiring issues with the new lamps. Following the standard path for the wires keeps it tidy.
REF ARTICLE - H4 Headlight Conversion