Need catalytic converters replaced prior to tune

[02Z71Raven]

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?

 

[Fless]

What year?

 

[swathdiver]

Magnaflow makes quality catalytic converters. The 6.2 Sierras use 3.5" diameter pipes for the cats and Y-Pipe and then a single 3.5" exhaust. Of course, they make 403 horsepower.

Most use 3" pipes. Stock is 2.75".

 

[Geotrash]

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.

 

[02Z71Raven]

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]

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.

 

[992dr]

I have had great luck with Magnaflow Spun Metalic cats.

 

[02Z71Raven]

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]

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]

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.