2nd cat...... What's it all about.....
 

So here's the thing. I've got a 2014 (new shape sti) whose stock exhaust needs replacing as its too quiet.

Now i could take the safe option n go cat back or should i go further?

Here's a stupid question? Does a "full" system remove both cats or just the second one? I ask because my last 2001 wrx had a "full" system but upon inspection, only the second one was removed (my understanding was that both were supposed to go?). It still sailed through its emissions test n when i tried to sell the second cat for scrap, was told it wasn't a proper cat but a "euro" cat. The bloke got a metal rod that passed straight through it as though it was hollow and gave me a couple of quid for it.

So what does it do, is it necessary and when i replace my exhaust should it stay or go if i still want to pass emissions???

Thanks in advance.

Just discovered that with the older wrx (not sure if this includes the more modern versions) in the uppipe there is a precat, so now I'm wondering if the reason why my old wrx passed emissions with the second cat missing was due to this and therefore if i remove the second cat from my sti, will it fail on emissions?

Should have mentioned in my last post that older sti's did not have the precat in the uppipe.