The 4th Generation Pontiac GTO (2003-2007) can be a little difficult to perform an HID conversion kit install because of the automatic headlights and the daytime running lights. The automatic headlights turn on when you turn the key in the ignition, and the lights do not turn off during starting. Also, the automatic headlights turn on the headlights when the vehicle is off and the remote locks key fob is used. Both of these things do not mix well with aftermarket HID lights. The DRL function (Daytime Running Lights) will turn on the headlights with lower voltage than normal and will cause the HID ballast to not power up properly.
Both the automatic headlights and the DRL function should be bypassed or disabled. Lastly, it is easy to do a quad-four headlight modification which will allow both high beam and low beams to be on at the same time.