as far as I now there was 2 cats in the last impreza I had. I had the back one taken out an it passed think its the one nearest the engine thats the one that will fail if its taken out. I stand corected on all that as I don't now a wrench from a spanner
Gerry is right I think. The New Age Imprezas I think came with 2 cats, downpipe and center section cat. I have heard of New Age Imprezas passing with just the cat in the downpipe and the center section cat removed.
i know a lad with an E85 powered 200sx, he passed the NCT with no cat in his so its is possible but not applicable in this case i think. someone said if your car is listed as supposed to having a cat and they visually see no cat they can/should fail you for that too