I have both, the NV5600 and the G56 and drive both regularly and 7th will engage when you turn your radio up, and not just AM but FM with the Sirius radio, especially when Heavy Metal is playing. But I also can reverse this by thinking the 7th gear is engaged but the RPM just wont drop back to the normal 6th gear range, and go back to 7th.
FWIW, the sun sets on the left coast were the commies are still trying to figure out a way to tax that sun setting. When we fall into the ocean, SD will be the new left coast and you will have the burden of figuring out a way to taaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaax any thing you can find. Oh, and the ejection seat is for my wife when she starts to mess with my knobs on the dash, you know I like 7th and I don't want her to know about it.