Exhaust ticking sound
 

Noticed this a few weeks ago but didn't think much of it.

After I've driven the car for a while and go to park it I notice a very fast ticking sound coming from the back of the car. Right around the diff.

This ticking sound is present with the engine on or off but only happens after driving for a while.

It's not causing any loss in drivability but it sure is annoying.

My exhaust is a custom build but the problem didn't start happening until months after the exhaust was done.

My theory is that it is the metal cooling down rapidly as the sound is not present at cold start or even after idling for a while.

Any ideas or has anyone experienced similar issues?

metal expansion / shrinking effect I believe. Its normal even on stock cars...soun like a tik tik tik sound?

Exactly. Any way of preventing it or muffling it without exhaust wrap? I don't really want to go down that path.