off the stock harness. Running an HID subharness is ideal to power the ballasts properly. You'd also probably be better off with an OEM ballast. Although you may think that the ebay ballasts work fine, the way they power up the bulbs is different. Quality ballasts (OEM) allow the bulbs to warm up more slowly, resulting in longer bulb life and they provide more consistent power compared to the junk Chinese ballasts. Just a suggestion, but the Philips bulbs are diamond-cut and not junk, so personally I'd want to maintain them. I used the have the Philips Ultinon kit and it was a great setup.