Need catalytic converters replaced prior to tune

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02Z71Raven

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Just got my truck back from the shop. Did a full break down of the 5.3, replaced just about every major component except the lower end. Stage 3 cam with DOD delete, but my mech says he can't tune it because I gave it to him with a full tank of regular gas.

Not the only reason he wants to wait though. Headers are done, I need to do the CAI and he says I need to replace the cats because they have 172k miles on them and are causing restriction.

Of course we discussed removing them completely, but I'd like to have cats, I just don't know what a good flowing replacement would be for a mild 400 hp motor without going og and/or breaking the bank.

Any suggestions?
 

Geotrash

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Just got my truck back from the shop. Did a full break down of the 5.3, replaced just about every major component except the lower end. Stage 3 cam with DOD delete, but my mech says he can't tune it because I gave it to him with a full tank of regular gas.

Not the only reason he wants to wait though. Headers are done, I need to do the CAI and he says I need to replace the cats because they have 172k miles on them and are causing restriction.

Of course we discussed removing them completely, but I'd like to have cats, I just don't know what a good flowing replacement would be for a mild 400 hp motor without going og and/or breaking the bank.

Any suggestions?
How does he know they are causing a restriction? I’ve seen these cats run 400K miles.
 
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02Z71Raven

02Z71Raven

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How does he know they are causing a restriction? I’ve seen these cats run 400K miles.
Don't know. Previous owner ran the vehicle for a long time with a misfire though, so I wouldn't be surprised. Cam was bad, alomg with bearings, lifters, push rods, rocker arms etc...
 

Geotrash

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Don't know. Previous owner ran the vehicle for a long time with a misfire though, so I wouldn't be surprised. Cam was bad, alomg with bearings, lifters, push rods, rocker arms etc...
Ah, that'll do it. A consistent misfire or dead cylinder will take out the cat on that bank of cylinders in short order.
 
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02Z71Raven

02Z71Raven

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My buddy recomended welding in dynomax bullets because they look like cats for inspection. I'd rather have a high flow cat though.

I'll check out those magnaflows 992dr mentioned.

Any other suggestions?
 

992dr

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Personally, I like the sound with cats for a daily driver family hauler. It's basically a tiny muffler haha.

From searching the Magnaflows have gone up quite a bit but, I think they are worth it. You can also look for ss spun cats and see what comes up. I think as long as they are metallic cores you should be good.
 

drakon543

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as stated above find out what a good cat setup you should be running. between your tuner and such they will give you the deets as performance is all they do. to get the cats u want it will be semi custom anyway so they just need to tell you type. order size to match what u have and get them welded in.
 

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