Quick catalytic converter question

ninjafury

New Member
Feb 23, 2008
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I'm helping a friend with his 94 GT. We just finished correcting an overheating problem thanks to HISSN50. Now we are trying to get the car to pass smog here in california. We have stock headers (I believe) going into a street x pipe with the smog pump still installed. What we plan to do is weld cats into an offroad x pipe, has anyone ever done this? Where should we position the cats in the pipe? Will this even work?
 
It'll work, I had cats welded into an offroad H before. I'm not absolutely sure where they should go, but if you use the air line as a ruler, it should terminate at the cats, giving you a good idea where you'd be looking to put the cats.
 
You could check out some photos of catted X pipes and see how they are in relation to the X and the header connection flange.

I'm guessing that 02 sensor outlets will determine largely where they will need to be located.

Clean the MAF sensor, as that will help a good deal if it is dirty. Maybe throw some Seafoam in the gas tank for extra measure.
 
Check with your local emissions folks. Technically you have to have the same number of cat housings (4) as the car came with stock. Our stock cats have a total of 3 stages in two housings per side, whereas newer cats do all 3 stages in one housing. So though you can have the correct number of stages, reducing the number of cat housings can create issues in some parts (this seems to be subjective based on the locale).
 
i was stationed in cali and had an off road pipe
when sticker time came i told them i had no cats and need some put on
they put two on and passed me

this was about 7-8 years ago

ask a few shops first and you should be ok , BUT ASK FIRST ANYWAY
 
I agree with JT. I would ask first Cali is more anal about their emisions then stuff is here and its pretty bad here. It would suck to go through the work to have them welded in then have them still fail you for something stupid.
 
thanks for all the feedback guys! I really appreciate it! We ended up finding a stock H pipe with 4 working cats in the local classifieds here. Very cheap too. Tomorrow we'll try to smog.
 
ha ha I don't do that though too much of a pain in the ass on a car with a 2" drop. Plus it has cats for the visual and it passes the sniffer. I told the shop guy that I was told they were hallowed out and he just said i don't wanna know. I've known the guy for ever so I knew he wouldn't fail me after I told him