hey ya'll... i'm a bit new to this engine hoopla, but what exactly is the difference between exhaust piping and cat-back piping. i guess i assumed the cat replaced it or something. anyone care to elaborate?

 

They're both the same, as far as I can tell from what you're asking.
A cat-back exhaust system is just what it sounds like: a custom/aftermarket exhaust system from the catalytic converter to the back of the car.
A complete exhaust system would include a header, high-flow cat and the piping and mufflers towards the back of the car.

 

Damnit Steve.. I should Slap you.