Do Aftermarket wireharness' still need headlight relay mod for headlights???

[piecesparts]

I suggest that you get the Aftermarket relay and harness. TWO reasons--1) the wiring harness may support the extra load, but the switch is still the same design inside--so a possible problem. 2) The use of the harness will guarantee that there is a full 12 volts at the headlights, not a percentage like you would have using the full wiring system and running the power through the dash and switch. The bulbs will last longer as well as being brighter.