High Flow Cats vs. OEM Cats

[Chaotic_Warlord]

Ok what exactly is the difference between a High Flow performance catalytic converter versus the OEm cats that come with the 240? I did a search on here for Catalytic converters and came up with 2 entries neither of which were helpful. Is there a real difference between performance cats to OEM cats.

If there is a real difference is there a specific brand that is better than others. I've only heard of Catco cats but the direct fit cats they make are OEM. magnaflow makes a HP cat but I havent heard anythign about them. Any help would be appreciated since I am looking to replace my full exhaust from the header back in the near future and I am looking to upsize to a 2.5" exhaust.

[skydragoness]

I went from a clogged catalytic converter to a hi-flow Catco on my white s13, obviously a huge difference. The only thing I can see is different with OEM cats vs Hi-flows, is you can actually see through them. I think OEM cats have a lot more baffles inside. That's about it. Supposedly Random Technology cats give more hp gain, but they're too expensive. I just ordered a Magnaflow hi-flow for my red s13 since i'm real pleased with the Magnaflow racing-series muff i had welded to my cat back.

[Scooby24]

A lot of what I've seen labelled "high flow" cats are really just resonators...they are straight through and perform no smog purpose.

As sky said, random makes a real high flow cat but they are expensive for sure.

If you're looking for 2.5 from downpipe back though it's the way to go. A straight pipe sounds like crap from what I've heard. I suppose it depends on the exhaust design....

[Scooby24]

here's one on ebay going for 206 bucks

http://cgi.ebay.com/ebaymotors...QrdZ1

[skydragoness]

A lot of what I've seen labelled "high flow" cats are really just resonators...they are straight through and perform no smog purpose.

....

wow, really? where have you seen that? particular brands? one would think they'd be in serious trouble if they were marketing something that was simply a resonator as a hi-flow cat, I never failed emissions with my Catco. Like i said, you can see thru the hi-flows, but it's a kaleidoscope thing, it's not a gaping hole as there is still some honeycomb packing in there. That's interesting to hear though.

[Chaotic_Warlord]

Well for 800 dollars I could go out and get me an HKS Cat, but I think I'll just pass on that right now.

[dfw240_EE]

So Random Tech cats actually work? They are $200. A pretty penny but not horrendously expensive. Consider that an autozone catalytic is $140 or so then I would say that the extra $50 or so dollars would be worth it.

[InsanityInc]

wow, really? where have you seen that? particular brands? one would think they'd be in serious trouble if they were marketing something that was simply a resonator as a hi-flow cat, I never failed emissions with my Catco. Like i said, you can see thru the hi-flows, but it's a kaleidoscope thing, it's not a gaping hole as there is still some honeycomb packing in there. That's interesting to hear though.

It's totally untrue. First off, a resonator is something specifically designed to cancel out sound waves, not just a piece of pipe. Plus, like you said, you can see the catalysts inside them.

[Scooby24]

It's totally untrue. First off, a resonator is something specifically designed to cancel out sound waves, not just a piece of pipe. Plus, like you said, you can see the catalysts inside them.

No it is completely true. Usually the ones I see that are just resonators are on ebay....labelled as "Resonator Hi Flow Catalytic Converter"....they state inside the ad that they are for "off-road use only" but many don't state they aren't actually a cat so if the buyer was not very savvy they would be duped into thinking they were buying a replacement catalytic converter.

Here is a said example:

http://cgi.ebay.com/ebaymotors...QrdZ1

You'd have to be pretty dumb though to actually think this is a catalytic converter.

Sky: what you bought is actually a catalytic converter if it has material inside it.

[dfw240_EE]

"off road only" is in the smallest font on the whole page.