I have been building, as have many others here on the 'Bolt, this mod for years. The idea is to get battery amperage and voltage to the lights by the shortest route. It does make your headlights noticeably brighter. I use 12ga wire and ceramic connectors as well as connector grease. I get the relays on ebay. See the schematic in my photo bucket by following the link below. My way is better made with better parts then any kit I've seen, so DIY and save a few bucks!
Best wishes,
Les