1. Be sure to read the owner's manual. There are a number of features in your GTO, such as the programmable instrument cluster, that are quite enjoyable.
2. Check your tire pressures. Now. They're set at something like 50-60 pounds in Australia for shipping purposes -- and some dealers don't bother to adjust them here. Check the spare while you're at it.
3. Be sure your floor mat retaining anchors are not broken.
4. Do you have your vehicle information card? It's around the size of a small index card -- with codes to your radio, ignition key, glove box key, VIN#, etc. printed on it.
5. Be proactive and get a good coat of wax on your car. In fact, I'd do a good job of cleaning the paint first. Use a clay bar or a product like Klasse All In One. That'll strip all the dealer applied wax off and remove anything that stuck to the paint. Then wax with Klasse silver. Apply a little extra to the front bumper so it won't get scratched when you punt Mustangs into the weeds. Johnnebgoode knows what he's talking about in this new car paint prep area. I'd like to hear his thoughts on this.
6. Dial in the Blaupunkt. Search this forum about how to do that. It involves adjusting the factory settings -- and turning up the boost from the trunk mounted amplifier. Since I don't have the time to write the full description -- I won't into it any deeper than that.
Otherwise, welcome to the club. You've got an awesome car.