Because the headlights split it was really easy.
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The harness is designed to go straight to the battery and the lights come on a few seconds after the engine fires up and they go off a few seconds after it's switched off (voltage sensing?) and there is a wire that "can" go to the side lights (works without this though) I assume this will dim the LEDs when you put your lights on.
The inline fuse in the harness is a real cheap exposed one though so I'm going to swap it out for a waterproof one before fully installing it under the bonnet.
The LEDs seem pretty good (not staring into the sun bright like an Audi or merc) but the wires are like angel hair so I soldered and heat shrunk some beefier ones to the end of them.
I drilled two holes for the cables to exit the headlight unit (not sure mine were particularly waterproof anyway) and will daube a bit of silicone around the wires.
The LED strips I secured in a very Heath Robinson manner by drilling holes in the internal reflector and then using wire twists (the sort that power cables are tied up with on new products) with the plastic coating removed, but there isn't much room for them to come adrift.