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Hollowed out cat?

1.6K views 7 replies 5 participants last post by  Cue-Ball  
#1 ·
Ok so I am replacing my trasmission so the exhaust tubing had to come out so I could drop it. Trying to seperate the muffler and the cat I managed to split the muffler open. Soooo since i'm replacing the rear portion of my exhaust system shoud I take the cat off and knock all the crap out of it so its hollow? Will this have an adverse affect on performance? I would get a new cat but I really can't afford the extra $100 for it right now. Having to replace the trans hurt me enough. TIA

-Mike
 
#2 ·
96ZJ said:
Ok so I am replacing my trasmission so the exhaust tubing had to come out so I could drop it. Trying to seperate the muffler and the cat I managed to split the muffler open. Soooo since i'm replacing the rear portion of my exhaust system shoud I take the cat off and knock all the crud out of it so its hollow? Will this have an adverse affect on performance? I would get a new cat but I really can't afford the extra $100 for it right now. Having to replace the trans hurt me enough. TIA-Mike
Let me fix this for you

96ZJ said:
This will have an adverse affect on performance. I should reuse the old cat because I really can't afford the extra $100 for it right now. Having to replace the trans hurt me enough. TIA-Mike
On some OBD1 vehicles, running without a cat showed some gains. On ALL OBD2 vehicles, running without a cat will hurt the vehicle (loss of power, millage, etc). In either case, that cat was put there for a reason. If you can afford a trans rebuild, you can afford a 60 dollar OBD2 cat from summitracing.com
 
#3 ·
The only problem you might run into with hollowing out your cat (other than possibly not passing the sniffer test) is the computer might throw some codes, there is an O2 sensor in the cat that might affect the computer. I am running a Carsounds cat on mine, it is NOT an ODBII compliant cat so we simply drilled a hole and welded in a bung for the O2 sensor, worked out sweet.

I have not need a smog since the work but am sure I will have no trouble.

AW just converted his 5.2 to a 5.9 and hollowed out his cat and the thing runs like a champ, he even passed a smog check here in Cali with a hollowed cat.

So the truth is you will be fine to hollow yours out other than possibly check engine light, but that is doubtfull AW did not get that.
 
#6 ·
I'd think that hollowing it out would have the same affect as removing it.I went from 14 down to 12.4 mpg when I removed mine.