Quite simple for those in the know......
What does a cat back system actually mean ?
Sorry if this is a really stupid question

 

on the classic impreza it has two cats one in the centre section and one in the down pipe, the cat back systems remove the second cat in the centre section so start from the first cat, the turbo back systems start from the turbo and replace both cats

 

So am i right in thinking that a cat back system has no cat from the centre section to the back box

A no cat back

 

I would interept a cat back system as retaining the first cat. its as it says from the cat backwards so it doesn't include the front pipe. a full decat on the other hand eliminates both the cats.
ken

 

Cat back. In any exhaust manufacturer's listing is just that...

So on a impreza..it's basically the back box! As it is a compete section that bolts straight on to the centre section, retaining all cats on the car.

Centre section. Or centre section decat to remove the 2nd cat
Downpipe, or decat down pipe to remove the 1st cat
And up-pipe or up-pipe decat for cars fitted with up-pipe cats

 

Im sure on the impreza that the cat back system removes the second cat and starts from the first cat to the back, and the back box is just called a back box not a cat back system, if that makes sense

 

Well the Magnex cat back system didn't...it's the rear section only. Second cat or centre section still remains original (unless your fork out to replace that too)

PPP removes the centre cat and also replaces the rear section....but a ppp isn't a cat back

 

If I were you I would contact the supplier, as each may have slightly different ideas on the interpretation of "cat back".
( IIRC some early classics had a cat in the up pipe, instead of one of the other sections, cant remember what MY this went up to)