Magnaflow Direct-Fit Catalytic Converters - 22628 | eBay

So the other day I was researching cats and there's a couple of things I don't think I completely understand.

I went in to autozone the other day and they told me that an oem cat will cost about $300.

Now, from my research I have learned that aftermarket cats can give you a little hp boost.

So why do the aftermarket cats like this one cost less?
Do they function properly? Will I pass smog with this cat?

Can someone educate me on this subject please?

 

If you in CA, should NOT USE this one.. it's non-CARB compliant, so probably won't pass smog.

 

Honda Civic 1996 98 Genuine DEC Catalytic Converter California CA Legal HON91657 | eBay

so im looking at something more like this right?
is there anything cheaper?
would it be easier to go to a junkyard and rip one off there?

 

Let's back up and ask, why are you replacing it in the first place? I think the CARB rated aftermarkets are basically identical to stock with no potential for higher performance anyway. The stock converter doesn't hinder performance much at all in the first place.

One from a junkyard you take your chances, it may be worn out and not work well enough to pass the smog check.

 

When I went from OEM to a bolt on Magnaflow cat, the difference was huge. It was like driving a different car. OEM is so much more restrictive.

That said, you need to go with a reputable seller on ebay and avoid the noname brands. A lot of those cheap cats are hollow.

Taking from a junkyard is illegal...anyway, most cars will have them stripped for the scrap price anyway.

 

The guy before me did something to it and was telling me that I should get it replaced. and he was telling me that it's the reason why the check engine light comes on. when i'm driving it seems to rattle and I was looking at it and there's a bolt that's loose but it wont budge.

so I just want to replace the whole thing.