What is that sound? I never noticed it before. After i drive for a while and come home parked in the garage, i turn off my engine. As i stepp out of the car, i hear continous ticking coming from under the car. Like its from the catyltic converter or something. Is it just the Cat cooling?

 

Yes, it's your cat and other exhaust components cooling.

 

metal such as that on your exhaust expands when it gets hot. the ticking you hear is the noise the metal makes as it cools and "shrinks" again.