How to replace the catalytic converter on a 2004 mazda3 2.3, and do I have to modify the new cat to fit the oxygen

Thanks for the info , but i need more help like how to remove it and replace it in steps such as if I have to remove or unbolt certain parts that obstruct the cat or not , and if I have to purge the cat with argon when welding it since its stainless, I know I might be asking for too much but I want to do everything right the first time to keep costs down, thanks.

Hi, Sorry but I work night shift and haven't had a chance to get online, I went to AutoZone to buy a catalyst converter and they told me that it could be the spark plugs if you could tell me what type my car uses so I can buy them and install them before y buy the converter and going with your directions , they say its either the 11709089-447 or the NGK ITR5F-13 6044 , but that it has to be the right ones or I can damage the engine, that would be my last question ,thank you.

Hi, Sorry but I work night shift and haven't had a chance to get online, I went to AutoZone to buy a catalyst converter and they told me that it could be the spark plugs if you could tell me what type my car uses so I can buy them and install them before y buy the converter and going with your directions , they say its either the NGK ITR6F-13 4477 or the NGK ITR5F-13 6044 , they werent sure because the first 04 models used one type and 05 and newer models used the other , they said that it has to be the right ones or I can damage the engine, that would be my last question ,thank you.

If you notice Both plug models are ngk but they are different.

Relist: Inaccurate answer.
I went to AutoZone to buy a catalyst converter and they told me that it could be the spark plugs if you could tell me what type my car uses so I can buy them and install them before y buy the converter , they say its either the NGK ITR6F-13 4477 or the NGK ITR5F-13 6044 , they werent sure because the first 04 models used one type and 05 and newer models used the other , they said that it has to be the right ones or I can damage the engine, I checked online and some places it says one model and some say it's the other, I really want to avoid using the wrong ones ,thank you.

I do apreciate Your help but first You gave a wrong answer for the catalyst, You said it was easily accessible and and thati could cut it off and weld a new one, then came back saying to forget about that and that it came as one piece and that I had to buy the whole piece , then about the spark plugs you said it used the itr5's and it turned out that you were also wrong, I happened to find a parts maintenance manual from Mazda online and it says it uses the itr6's and it clearly states that if you use the wrong ones it will damage the engine, I would've given you a good score but those two wrong answers could've cost me a lot of money, which is what I wanted to prevent in the first place Im tired of wrong diagnosis with local ripoff mechanics and that's why I turned to you guys but it turned out to be the same thing, don't take it personal but just look at it from my point of view, Im sure you would feel the same way.