Cat size question

[Fubar]

I need to replace the 2 cats on my 98 expy. Does anyone know what size they are? I got a price quote to do this and want to see if I can find the cats any cheaper

 

[BIGRED03]

I have seen online that a couple direct replacement companies offer new cats as an option.

 

[Fubar]

Well I have a price quote to make a custom exhaust from a shop and heyd weld up the new cats. Would size of cats be an issue since its a custom true dual setup?

 

[BIGRED03]

I do not know about the size of the cats. I think it is an effectiveness issue of removing the extra unburned gas from the exhaust. Probably a displacement question. Do you have emission testing?

 

[FordandPolaris]

I do not know about the size of the cats. I think it is an effectiveness issue of removing the extra unburned gas from the exhaust. Probably a displacement question. Do you have emission testing?

That last question is important. If you do not have emissions testing, then you can do hi-flo cats from magnaflow or something depending on the system you are going to do, or just leave them out altogether. It does depend on whether you will put in a muffler or just leave it straight piped. These motors need some back pressure to keep the torque.

I have never had to do emissions myself so I do not know how the test works. If they just check for a CEL, then any cat should work since the downstream O2's simply read whether there has been a change in the exhaust detected (therefore meaning the cats are doing their job), but if they actually test the exhaust at the end of the pipe, then you will want to look for OEM replacements online. Most of them will say 50 or 49 state legal if they are applicable to your state's emissions laws.

 

[215Expedition]

We have to do emissions here in PA, so i can't install high flow cats?

 

[Fubar]

It's strictly plug in the OBD II and that's it

 

[BIGRED03]

It's strictly plug in the OBD II and that's it

No tail pipe sensor for emissions test? Why bother? I would contact the maker with that question.

 

[Canadian Expy]

We do a plug into the OBD port emission testing here, we use to do tail pipe but found that if the motor isn't throwing codes it usally will pass the test.

I run 2 high flow magnaflow cats on mine got rid of the 4 stock units.