I’m looking for a medium grade fix not looking to dump the bank on that.
Aren’t we all looking for a less expensive fix to any problem? It really isn’t up to us, now is it?
Check for exhaust leaks near the rear. Leaks can sound like clicking and is worse under power.
While you are under there, check the front differential bushing. The sound is more of a clunk than a click but if it is starting to fail, might be the issue.
Strongly suggest joining a CTS-V specialty forum for this rather unique car. Especially when you need to replace one of those weird 6 bolt wheels from a pothole or curb strike!