n00b question about exhaust
 

Very new at understanding how this all works...
I see talk about catted headers and catted front pipes.

My first question is how may cats does the stock BRZ/FR-S have (I always assumed 1).
Then, is it in the header or the front (I always assumed those were 2 different parts)?
Assuming it's in the front pipe, if one replaces the header with a catted header, does it mean one's now running 2 cats?
Same question goes in reverse (if cat is in header and one replaces the front with a catted front).

Again, very new at this... :(