Another dealer? The 05 GTO has a plug and play feature. I just installed a JHP set of gauges, and all I had to do was fish the wires from the side of the air conditioner duct above the radio. Good grief, send your dealership to JHP website, they have the long way online. I did not have to do all that. A good flashlight and a modified coat hanger and a lot of time. Well, do a search, you will come up with all kinds of good advice.