Whats a catback exhaust?

It is exhaust system from catalytic converter to rear of vehicle.

Comes with clamps, instruction and sometimes exhaust hangers.

[ not included catalytic converter.]

technically, in basic terms, a catback system is just a system that goes back from the catalytic converter. (normally removing the muffler.).

cats aren't as bad as they used to be, so most of the time there isnt a need to remove them.

mufflers have actually gotten worse, being that people like quieter cars. less restriction = more power. simple as that.

think of an engine as an air pump. air you can put in and push out in a given amount of time the more power it will have.

It will be perfectly clear if your re-read your question exactly as written. A cat-back exhaust system is ANY configuration of a split fake dual pipe AFTER the catalytic converter.

it depends. how much you want to spend. it can be just the muffler, muffler and pipe up to cat., or can include an after market high flow cat. or it can be the entire exhaust system form the down pipe all the way to the muffler. of course the more there is the more expensive it will be.