Depends on what HID kit you go with... The digital ballasts barely draw more current on startup than the standard 55w halogen bulbs do while running. That being said, I would still use a relay in any aftermarket setup simply to isolate it from the rest of the system.I converted to HID lighting for my low beams and fog lights. You must add a relay to the ballast for the low beam and one for the fog lights. The ballasts draw too much current.