Exhaust problem

[Weirsy]

So for a while now Ive had this weird rattle when the engine is reving down while its hot and i figured it was my cat so i swapped it with a 3" test pipe. While i was under there and removing the cat i noticed that the connection between the downpipe and exhaust pipe before the cat was loose and i pulled it right out with no force at all. looking inside i see a clogged mesh/screen and i'm wondering if that is restricting airflow?

Basically this loose connection i speak of is what i now believe is causing my rattle so i want to get it welded back together but if the clogged screen is a problem i will probably get it looked at closer.

Ive also been told that our cars (obdii s14's, mines a 97) have 2 cats, so the 'down pipe' i referred too might be better known as the first cat but i'm not entirely sure.

Should i just get this connection welded back together or should i have the first 'cat' replaced as the screens inside seem to be clogged and slowing air flow?
http://i11.photobucket.com/albums/a199/Weirsy/exhaust003.jpg

[rollhard]

Its hard to tell from that picture but it looks completely clogged. The cat's internals should look like a honey comb type of material. If you want to get a highflow cat, I recommend Carsound or Magnaflow (Carsound makes the Magnaflow ones). I have tested these over and over in the past. The 2.5" Carsound high flow cat will outflow the RT 3" cat. They are fairly cheap also at about $95 each.

[miked808]

What I did was replace the first cat or pre-cat with a stock SR Downpipe and extended the o2 sensor in the precat to after my Highflow cat.
http://img205.imageshack.us/img205/1299/pict00133gt.jpg

[Dorifto180sx]

It could possibly be inside the muffler itself. Do you have a cheap after market muffler or stock? Cause I use to have that weird rattle sound when i go low or high revs. It got annoying and loud. And I soon got a GP Sport exhaust and no more rattle. Shake the muffler and try to listen if it sounds like something is inside.

[S14DB]

Yeah, that's the primary cat on the S14's and it looks melted. Prolly why the flange melted. Time to get a new one.