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Can someone confirm info on a new cat?

hockeybawler

New member
My cat has gone bad on my 04 grand prix. From what I have read, I can get away with a 3" 400 cell cat from zzp and most likely not throw a code. Can anyone confirm that I have understood this correctly?

Car is 04, topswapped, speeddaddy headers with new flexpipe, borla mufflers, and zzp tune. Thanks for the help in advance.
 


You'll probably set off that code with a high flow cat. You can go to any auto parts store and pick up a spark plug anti fouler to place between the o2 sensor and the bung to resolve the issue. It's a couple dollar fix that seems to be pretty successful.


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What would you go with if you were in my position? Just a regular store bought one or a high flow cat? Also, is 3" correct or should I go 2.5"?
 
If you have headers then you'll need a 3" cat. Personally I'd either run catless or replace with a high flow cat and have the codes deleted either way


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I don't recall the part number off hand and I'm sure it's changed by now but magnaflow does sell a higher end cat converter that works far better than the high flow cats.

I think they still might call it a high flow converter but it is double the price of the cheaper $50 dollar cats that you can just toss in there.
 
So what did u do with the speed daddy headers? U had a new flex welded in and then cut a section out to have a catwelded in and its bad already? How long have you had I like that?
 
With the headers I had the flex cut out and a new one welded in since mine leaked from there just like others who have speed daddy's. I havent done anything with the cat, this is still my stock cat and I have had this combo now for about 4ish years.
 


I'm still runnin my SD headers with no leaks yet, SD flex and only used bandclamps on the 3 in DP the rest has just better U bolt style clamps..no rtv on nothing my slip joints were super tight so I didn't see the need to use it
 
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