Curt Manufacturing is making a hitch for '04 and '05 GTO's. I bought mine from DropHitch.com for $119. It has an excellent, shiny black finish and comes with installation instructions. I have photos posted of the installation at: www.tanglewoodbrushstrokes.com
Go to Jerry's Page.
After jacking up the rear of the car, you must remove 12 plastic pins that hold the black plastic cover under the car. This plastic cover includes the piece on the right side of the car that runs over to the right side of the rear bumper cover. You do not need to detach this right side piece from the center piece. There are also three bolts that are to be removed, two in the center of the plastic panel and one towards the front of the car. You will discard the two bolts in the center. The cover is not removed, but dropped down to give access to the underside of the car.
Once the cover is down, you will see a series of studs sticking down towards the rear of the car. The hitch attaches to two of these studs with one stud being a larger diameter than the other one. The other two attachment points are where the two center bolts were previously removed. The kit comes with two longer bolts to replace the original factory bolts and with the necessary nuts and washers to attach the hitch to the studs.
Once you have the hitch bolted on, you will have to cut out the two raised round areas on the top side of the plastic cover where the two center bolts were attached. This is to give clearance for the hitch where the bolts attach the hitch to the body of the car. As you will see by the photos, I did not spend much time making these pretty as they are hidden once the plastic cover is re-attached. Re-attach the cover and you are finished.
I also installed the wiring for my trailer. It uses the four pin flat connector. You will need an electronic tailight converter which I purchased at Wal-Mart. To access the wiring, you will need to remove the plastic panel inside the trunk at the rear. There are four screws at the top hidden by plastic covers that are easily removed. There are also six plastic fasteners to remove. Once the panel is out of the way, you can pull back the carpet on both sides to expose the wiring on the tailights. I also removed the carpet covering the spare tire.
There are five wires to hook up with the converter.
-hooked up to top bolt on the left side under the tailight housing.
-spliced into the blue/red wire on the left tailight plug
Green-right turn signal
-spliced into the blue wire on the right tailight plug-Since all the other wires were coming from the left side, I ran a separate wire from the right to the left side and then attached the wiring harness there.
Yellow-left turn signal
-spliced into the blue wire on the left tailight plug
-spliced into the brown wire on the left tailight plug
I then placed the wiring harness in a plastic protective cover. When not in use, simply place the wiring in the spare tire well. To use, run the cable to the rear and close the trunk on the cable.
Put everything back together and you are done!!
I have a motorcyle trailer and a bike rack that attaches to a hitch which I am looking forward to using.