I used to get a weird 1-2 thunk w/ stock clutch/flywheel/line when cold.

Now I get that thunk occasionally (not all the time), right before I fully stop w/ an aftermarket clutch and flyheel (OS Giken STR--integrated dual clutch and flywheel). The STR came w/ its own throw out bearing. I don't mind the noise so long as its not adversely affecting the tranny...

 

It is called "parade clunk" and it's common in some newer rear drive cars. Especially the CTS-V. We have gotten used to it. It can be caused by a dual-mass flywheel, but mostly in the joints of the drivetrain. If you hold the brake and a little gas (on a standard) then partially engage the clutch and very quickly release it you will notice it. If you drive smooth as silk, you will never hear it.

 

The Zip tie sound - I have that - what a good way to describe it. I have been complaining to the dealer of creaking when I get on or off the gas they don't hear a creak. Maybe if I say it sounds like a zip tie they will recognize it.