The headlights on my EVC were so dim that I was scared to drive at night. I purchased the wiring harness kit and the European headlights as you are considering. It included two new relays that are wired to the battery and triggered by headlight switch when the switch is turned on. It had no effect on the Driving lights. The new harness improved the headlights so much that I have not installed the European headlights yet.
Highly recommended.
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I thought the harness install was straightforward, actually easy.
Barry Black