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Discussion Starter · #1 ·
Well I am in the process of replacing my head gaskets on my truck, 2002 Frontier XE, Crew Cab, 4x4. While working on the truck I have come to relise my exhaust system is severly diseased / rusted beyond repair and probably well past being replaced. I have read through the exhaust threads and done a substantial amount of reading online.

There are several variations of exhaust around the 2002 model year for my truck and it has been difficult to find the correct parts to replace. However my question is more to the post / secondary CAT's on our trucks. They are expensive to replace and appear not to be monitored by the emission system. I say this because the oxygen sensors are upstream from the sencdary CAT's. I live in an area that performs yearly inspections and the inspection report does appear to print out some gas information which leads me to believe they are sniffing the tailpipe. The question i have is can the secondary CAT's be deleted without requiring an oxygen sensor fooling device, and where can I get a direct fit test pipe? I will add that I had a huge hole in my muffler the last time I went for my inspection and the tailpipe gas readings where exactly the same as the previous year without the hole. Dont know what means but just more information.

Looking for some input from peeps who have performed the mod or know where I can more information.

TIA
 

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From what I understand the secondary cats are hollow anyway, so it shouldnt matter if you get rid of them.
 

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Discussion Starter · #3 ·
Not sure this is the case, can someone confirm. They cost a fortune $200 each so I'm sure there is at least some CAT material inside them.

Any other recommendations, i am not trying to make extra power or create more sound or circumvent the emissions just looking for a cheaper alternative.
 

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yes you can remove the seconday cats without getting an ses light. when you remove the primary ones is when you need to fool the ecu somehow that the cats are still there.

Also on a side note, if your state does bi annual emissions testing you'll most likely need all your cats.

My 99 fronty 2.4l wouldn't pass smog with just one cat, I needed both to get the numbers down.
 

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Discussion Starter · #5 ·
Thanks 1fstmax thats what I was thinking, the smog check would be an issue as they do record the readings here as well. Guess I have no choice at this stage but to replace them and move on.
 

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none of the CATs on the vehicle are hollow. do not remove/delete them unless you have a reson to do so (i.e...offroad rig and not a daily driver). the primary and secondary CATs serve different purposes and remove different particles and waste from the exhaust.

a cheaper alternative than buying new stock style CATs would be to use a universal style high flow CAT. magnaflow has some good ones and i have had some of these installed on another vehicle. can be bought for less than $100 each and no worries regarding emissions and/or sniffer test.

if you don't know a bunch about the secondary CATs, go to an exhaust shop and let them help you find the right ones for your application. inlet and oulet size need to be considered as well as length and diameter. pretty easy job for a good shop.

Magnaflow Performance Hi-Flow Catalytic Converters - JEGS
 
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