True. I have not had power problems since I changed over to the relay kits. I have sound systems in both my cars.
The chevelle has a 2000 watts RMS stereo. I run two batteries. One dedicated to the soundsystem, one for Starting, these are seperated by a high amp solenoid. I also have Fuel injection, Dual 12" electric Fans, MSD box, Mini starter, two amps, electric fuel pump, and a digital Dashboard. As you can see I have enough accessories to power.
Headlights do take away some power when you turn them on. The typical HID like bulb is usually anywhere from 65-110 watts or so. The take a bit of juice to run them. There is a voltage drop when you turn them on. The drop is more signifigant in the Hi wattage bulbs as compared to the HID bulbs. The HID bulbs are just more efficient. Like I said I have both, and they both work very well. Its just the HID lights are more efficient0.
Tim