2 Cats am I right ?
 

I have owned an MY02 for bout a month now.
Am I right in thinking this car has 2 cat on it. One one the down pipe
and one in the centre section of the zorst.
If so which one is the best to decat, and will I then still be able to pass
MOT as it still has one.
Or am I talking out my arse :)
Any help appreciated..

ta

the easiest and cheapest is the one in the center section as you can buy its and simply fit it if you can get under the car. Kwik fit or someother place with ramps should be able to do it.

Not to sure out of the two which would give the best performance upgrade on there own.

MY02 what? UK WRX? STi Type UK? Japanese market WRX/STi?

Yes/no. If you have a UK WRX, it has three cats, the two you've listed plus another in the up-pipe between exhaust headers and turbo.

In performance terms the downpipe. In "still being able to pass the MOT with confidence" terms, the centre section. The up-pipe one is somewhere in between, although it's definitely worth getting rid of if you plan further mods.

The downpipe one is the best as it'll give you an easily noticeable improvement in throttle response and overall performance. Whether or not it'll still pass an emissions test with the other two in is, to a certain extent, down to luck and the condition the existing cats are in.