You would be completely wrong. But hey, you came here asking for help. Oh well. I'll let you trouble shoot this to the moon. And when the dealer and everyone else tells you its normal, then maybe you will believe. Shit, head to the dealer and test drive a cold one. They will all do it. There are people here that work at dealers and drive these on a regular basis cold and have commented on how they do it normally. The cam phasers are at the top front of the valve covers and it takes the oil a little time to get up there.
Otherwise every GT I have been in, including two of my own were "pinging" from the factory....lol I guess you just figured out the #8 issue indirectly....LOLOL.
Just the fact that you are so sure of the cause, without hearing the sound yourself says a lot about your level of "expertise".
Yes, I did ask for input, but you don't have to get butt hurt when I am not on board with your idea.
What kind of background do you have in mechanical things and engines that qualifies you to make flawless diagnosis via the internet? How long is "a little time" for the oil to get to the cam phasers?