'08 Silverado 4.8 - Bad Converter - Opinions on Magnaflow Converter

T

TXCarGeek

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After 208K miles, seems the bank 1 converter on the Silverado has finally given up with bank 2 not far behind. Verified it using my scantool and sure enough, the post cat (sensor 2) voltage is mirroring the pre cat (sensor 1) voltage.

I'm wondering if anyone has used the bolt-in/direct-fit converters from Magnaflow on their GMT-900 truck/suv? Cost is $766 vs $1200 for the OEM part.

Link to the MF converter: https://www.magnaflow.com/products/...ompliant-direct-fit-catalytic-converter-49194
 
We sell them all the time at work and very few warranty returns. And I suspect most warranty returns are caused by some other issue not the quality of the product. I’d feel comfortable putting a Magnaflow cat on my vehicle.
 
dogememe said:
We sell them all the time at work and very few warranty returns. And I suspect most warranty returns are caused by some other issue not the quality of the product. I’d feel comfortable putting a Magnaflow cat on my vehicle.
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Good to hear. We put some weld-in magnaflow converters on my brother's '08 Navigator over the summer and haven't had any issues with them thus far. The direct-fit option for that vehicle was about $2k vs $500 for the weld-ins. The direct-fits for the Silverado are much cheaper and I would like to give them a try.
 
TXCarGeek said:
Good to hear. We put some weld-in magnaflow converters on my brother's '08 Navigator over the summer and haven't had any issues with them thus far. The direct-fit option for that vehicle was about $2k vs $500 for the weld-ins. The direct-fits for the Silverado are much cheaper and I would like to give them a try.
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At least from what I have observed the fit&finish of the Magnaflow direct fits is nice. Quality stuff. Although we sell a lot more of the universal cut&weld cats. Well, I should say weld. The cutting has already been done by the cat thief. Lol.

But now compare that to the Walker exhaust products. Omg. Looks like trash. I’ve never welded a thing in my life but give me a welder and an hour to watch YouTube videos and practice and I could make a better looking result. Lolol.
 
That's good to hear...fit&finish was the main thing I was concerned about. I suppose I could also go the weld in route...they're $228/each and I have a local shop that can weld them in for likely under $100. Decisions decisions lol

Looking at the walker pieces that are shown on Rockauto...yeah, just looks cheap lol. I like that the Magnaflow looks to be mandrel bent.
 
Looking at the direct fit and weld in converters more closely and the direct fits use spun design converter while the the weld in used the more traditional clamshell design. I do like the idea of a spun converter
 
Not to pile on with complaints, but I just have to say walker USED to be a good product but in the past couple of years their welds look like someone needed more training and/or prescription eyewear! Sad whoever bought out Walker..

Does a spun converter need any "breaking-in"? I know the honeycomb design in my civic needed to be broken in before using it. It was starting the car, letting it idle until the cooling fan came on, not touching the gas at all, then letting it cool completely, then starting it and driving it.. It was something like that.. Just wondering that way your new converter will last you a long time!
 
Is the converter clogged or melted and causing driveability issues? If not, I'd leave it alone before spending $766 letalone $1200 for an unnoticeable repair.
 
atikovi said:
Is the converter clogged or melted and causing driveability issues? If not, I'd leave it alone before spending $766 letalone $1200 for an unnoticeable repair.
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It isn’t, seems to have just lost efficiency. I just really hate check engine lights.
 
A different GM application, but the direct fit Magnaflow on my Buick V6 seems very well made and has passed emissions easily since 2018. Definitely more free flowing than the original, but not too loud. It did surprise me. The original rattled at 200K, now at 258K.
 

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There is nothing wrong with the Magnaflow converter, it's no worse than any other brand, but if you live in an emissions county and plan on keeping the car awhile, you should consider a CARB-approved California-spec converter, even if it's not required. Unfortunately, the CA aftermarket cats for your car actually cost more than OEM from the dealer :sneaky:
AP's CA cat is special order and $1500, while Magnaflow's costs $4500

Federal converters other than Eastern only have a 2-year/25k warranty on catalytic performance, while California requires a 5-year/50k warranty. Eastern's warranty is 5 years/50k even on federal cats. OE cats have a warranty of 8 years/80k

The FVP converter listed on Rock Auto is probably reboxed Eastern, as it has the same 50k warranty that Eastern provides :unsure:

So, I would recommend the FVP cat, along with oxygen sensors that ship from the same warehouse. You should replace all the oxygen sensors on your car, upstream and downstream.
 
slacktide_bitog said:
There is nothing wrong with the Magnaflow converter, it's no worse than any other brand, but if you live in an emissions county and plan on keeping the car awhile, you should consider a CARB-approved California-spec converter, even if it's not required. Unfortunately, the CA aftermarket cats for your car actually cost more than OEM from the dealer :sneaky:
AP's CA cat is special order and $1500, while Magnaflow's costs $4500

Federal converters other than Eastern only have a 2-year/25k warranty on catalytic performance, while California requires a 5-year/50k warranty. Eastern's warranty is 5 years/50k even on federal cats. OE cats have a warranty of 8 years/80k

The FVP converter listed on Rock Auto is probably reboxed Eastern, as it has the same 50k warranty that Eastern provides :unsure:

So, I would recommend the FVP cat, along with oxygen sensors that ship from the same warehouse. You should replace all the oxygen sensors on your car, upstream and downstream.
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The non carb converters are far worse than anything else. BTDT. Could barely pass NOx with a generic non carb converter, when I put an OE on it went from 1100 to about 10.

The Carb ones are likely a happy medium for a higher mileage vehicke that one wishes to keep running. The others… trash.
 
slacktide_bitog said:
There is nothing wrong with the Magnaflow converter, it's no worse than any other brand, but if you live in an emissions county and plan on keeping the car awhile, you should consider a CARB-approved California-spec converter, even if it's not required. Unfortunately, the CA aftermarket cats for your car actually cost more than OEM from the dealer :sneaky:
AP's CA cat is special order and $1500, while Magnaflow's costs $4500

Federal converters other than Eastern only have a 2-year/25k warranty on catalytic performance, while California requires a 5-year/50k warranty. Eastern's warranty is 5 years/50k even on federal cats. OE cats have a warranty of 8 years/80k

The FVP converter listed on Rock Auto is probably reboxed Eastern, as it has the same 50k warranty that Eastern provides :unsure:

So, I would recommend the FVP cat, along with oxygen sensors that ship from the same warehouse. You should replace all the oxygen sensors on your car, upstream and downstream.
Click to expand...
At this point I'm leaning towards just getting some weld-ins from Magnaflow but I want to see if they have some spun-body weld-ins as opposed to the clamshell design. I am not in an emissions county, but the longer warranty of the non-CA FVP is appealing.

Actually just added the o2 sensors to my cart on rockauto. Along with a few other odds and ends that I've been needing to do.
 
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JHZR2 said:
The non carb converters are far worse than anything else. BTDT. Could barely pass NOx with a generic non carb converter, when I put an OE on it went from 1100 to about 10.

The Carb ones are likely a happy medium for a higher mileage vehicke that one wishes to keep running. The others… trash.
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Had some weld-in eastern converters installed on my brother's vehicle and they lasted 6 years before throwing a code. Installed weld-in Magnflows being that the vehicle has 275k miles.
 
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