Question about Cats

[Caliptix]

OK here is the problem. I know that I need new cats.
I bought a pair of magnaflow universal cats that have to be welded in. The problem is I can't get a mechanic around here to do them. They say that once you weld them in there are noting but problems and I would need to get the direct fit , the ones that bolt on and come in a one piece y pipe style.

Has anyone heard about this? 4 different mechanics told me this today.

 

[hassoun]

i swapped mine about 2 months ago. i never had issue since. i love them. they have better flow and sound meaner. i dont like the flowmasters sound so i went with magnaflow cats and muffler as well. a guy i know charged me $150 to weld them on. i dont see why they wouldnt weld them for you. if they give you problems (they wont) its your problem not theirs. also make sure Justin from blackbear disables your rear o2 sensors or your vehicle might fail emissions.

 

[Caliptix]

right but its only been two months. The mechanic told me that it normally happens 4 to 6 months after they are installed.

 

[KrautBurner]

I'm running two 3" high flow cats on my GTO
had them on for about 3 years/30K miles no issues
but I got a tune.

also,
I've had aftermarket cats on several other cars (gto being the only OBDII vehicle tho)

 

[hassoun]

excuse my language but your mechanic is a certified idiot... go somewhere else.

 

[Caliptix]

i dont know man 4 mechanics can't all be wrong

 

[sumo]

i dont know man 4 mechanics can't all be wrong

if they are all from the same shop they can be, lol

 

[Jay]

The aftermarket cats have virtually the same catalyst in them as OEM, just with a less (emission-reducing) efficient design so they don't restrict flow as much.

Some shops are skiddish about messing with OEM emissions equipment because they don't want to be held liable by regulatory agencies should something on the matter come up. Plus on many modern engines with all the very picky emissions equipment and programming, aftermarket cats might trick the PCM into thinking there's a problem and might throw a code.

I've welded in aftermarket cats on some of my old street-toy cars before and ran 10s of thousands of miles through them without issue. That was while making over 800hp, which REALLY loads those cats with stuff to clean up and they never gave me problems. Of course, I didn't use the downstream O2 sensors (programmed them out while on the dyno).

 

[BOSS]

i dont know man 4 mechanics can't all be wrong

What they are talking about is fitment. I'm guessing they weren't very experienced with mandrel bending. Call up a local performance shop that specializes in building motors, tuning or selling engines. They'll point you to the right guy(s).

I think they don't want to be on the hook for installation problems, but if they do it right - there aren't any

They need to unbolt the existing y-pipe, cut off the cats with a sawsall and burn in the new ones. I dont see how it's any more complicated than that.

x2 on the emissions skittishness, but that's mostly for removing the cats altogether. It's a huge fine if they get caught installing cat-less exhuast. BUT to get around it, you can do the install as an off-road use only.

anywya, good luck
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