Catalytic converter question

[Rubie_25GT]

So I know that the 1999 Legacy GT was an odd ball compared to its earlier brothers from 1997 and 1998, but how many catalytic converters does it have? I have counted the two that come off the headers, but it I have large bulge at the beginning of the mid pipe/resonator pipe which connects to the muffler pipe. It goes:
]=(Large bulge)=====(smaller hotdog bun bulge)=======[

This Large Bulge looks just like the first two cats, with a shield around it, but I have not looked inside of it. The reason I ask is because it is making a rattling noise and I am not seeming to get the best of gas mileage right now (all synonymous with a bad catalytic converter). I know the second cat on my car didn't have an o2 sensor in it and only the first one does. I am thinking this is the same thing with that large bulge on the beginning of the mid pipe from the second cat. I hollowed out my second cat to be just a open chamber and am also wondering if that could have heat up that POSSIBLE third cat to the point of breaking.

any help with understanding what it is would be appreciated so I can rule out the possibility of it being anything other than a useless bulge for resonation :smt017

Thanks!

[harrymaneuvers]

I think you have either 2 or 3 cats depending on if your car is a CA spec legacy or not. If it is... I would imagine they have 3 instead of two.

You should have two O2 sensors either way.

Pictures of which areas you are referring to would be helpful.

[Rubie_25GT]

unfortunately I do not have a camera at this moment. But i have a link to a diagram:
http://www.DealerDirectParts.com/1999-S ... -leg-4.htm (http://www.DealerDirectParts.com/1999-SUBARU-LEGACY-Exhaust-Pipe-p/subaru-5822737-leg-4.htm)

It is marked number 4 on the chart (it is the resonator pipe with that large bulge before the smaller hotdog bulge. It is rattling when I rev the motor sitting still or drive it. It will do it cold or warm, doesn't matter.

[Rubie_25GT]

:roll: and yeah your right I do have two sensors but they are all in the first cat and the second one doesn't have a hole. Forgot about that lol

[decke48]

Its a resonator. Not sure if it has fiberglass in it or not

[Rubie_25GT]

alright I can start ruling out some stuff now. Going to check it tomorrow and make sure that is correct. Thanks for the help!