In the new shape vitz its not under the car...its right at the start of the exhaust system just under the headers (thats the main CAT) the 2nd cat is near ur tail pipe n it isnt usually choked...the one near the engine is after being run in Pakistan for around 30k km. so it depends whether ur car has been run 30k km in Pak or not.
I used to own a 06 vitz n i also got my cat removed but later on someone told me a better solution which i wish i shuda tried first before removing it....basically removal means breaking it (its ceramic) so thers no goin back...if u wana install a new system its gonna cost u around 25 thousand so dont think on those lines.
What i wish i shuda tried first was to clean it....yes it can be to some extent....have its whole assembly taken out at a workshop and drip small amounts of sweep mixed with a bit of water from the top...let it drip thru ur cat onto the ground....keep doin this with small amounts of sweep mixed with water. Do this for about an hour. Then let the Cat dry up in sun....u'll see its gonna be clean of most of its lead accumulation. Just take care u dont touch the sweep with the side walls inside the assembly...coz the cat is attached with the side walls thru a cotton mesh n that will get damaged....so be very specific to drop that acid only on the middle part of that cat not the side walls.