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But said Venom cat doesn't work at lowering emissions, and isn't even legal. Best flow would be a single cell cat, just punch the stocker out. Unless the OP gives us some idea of what he wants the cat to be good at, I can't suggest the best cat...

Shame, it takes more energy to make a cat then sell it to us suckers, than it would ever save in emissions. We are better off capturing carbon from the atmosphere in ice blocks, or simply running ethanol in all vehicles that will run on it, as in Brazil.

They're not about global warming style emissions. They are about NOx and CO. CO is poisonous, and in heavily built up emvironments the amount of CO from vehicles is a serious health hazrad (or it was...before decent cat converters). NOx is both a greenhouse gas in its own right, poisonous in its own right, a trigger chemical for photochemical smog (which causes high ozone concentrations in the lower atmosphere - which is not good) and is a very bad thing to have in the upper atmosphere when it eventually gets up there. NOx is worth stopping. Most of the work I do in gas firing in industrial installations is about reducing NOx emissions. I have clients spending hundreds of thousands of dollars on CFD modelling to predict the NOx generation of new burners we design for them to try to keep the EPA happy.

The less cells, the more free flowing it will be, the more cells the more restrictive.

The less cells the harder it is to be EPA compliant, the more cells the better scrubbing it is.

So if your worried about EPA go for a 300 cell high flow, if you want power, punch out your old substrate and just leave a shell there so the police dont notice a decat pipe, if you get a EPA defect bolt a stocker in for the test.

There will not be much of a change in sound by changing cats, change the hot dog for a straight through muffler for the next noise level down or just add a straight through muffler....

About running a straight pipe instead of a punched out cat, its financial suicide, any idea about the on the spot fine for not running a cat? At least it wont be obvious to whoever checks the car when pulled over.

There will not be much of a change in sound by changing cats, change the hot dog for a straight through muffler for the next noise level down or just add a straight through muffler....

About running a straight pipe instead of a punched out cat, its financial suicide, any idea about the on the spot fine for not running a cat? At least it wont be obvious to whoever checks the car when pulled over.

A straight pipe through the cat, inside it, not cut out the cat and replace it.

The hassle is, if they drop the cat it will be obvious, if they measure the heat of the cat it will be colder than the pipe. At least if they see the insides are gone, there is no way they can fine you, as it obviously just dropped out one day officer...

Don't ever try and punch out a metal cat, only attempt it on the stock ceramic ones.

Don't ever try and punch out a metal cat, only attempt it on the stock ceramic ones.

It can be done, I did it in 5 mins the other week. Bit of inch pipe and lump hammer.

Which leads to my next point, metal cats arent worth the space they take up. Iv killed my second well known brand 100 cell cat in less than a couple of thousand kms. They are rubbish. They get hot, fold over and holy back pressure.

The 'best' cat for purpose is a bf xr6t cat, 3 inch, and mine was running euro3 standard on the emissions test.

You must be buying crap cats Amon. :P

The Xforce substrates are welded to the body, they won't move ever, and punching one out took me over an hour. Quicker and easier to make a pretend one from 4 inch stainless and two reducers.

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A straight pipe through the cat, inside it, not cut out the cat and replace it.

The hassle is, if they drop the cat it will be obvious, if they measure the heat of the cat it will be colder than the pipe. At least if they see the insides are gone, there is no way they can fine you, as it obviously just dropped out one day officer...

Don't ever try and punch out a metal cat, only attempt it on the stock ceramic ones.

That is the best way, the chances of them dropping the cat is zero at the point your defected, you usually have a time frame to bring the car in for a check, enough time to put a stocker back in to pass emissions testing.

I run a 100 cell FIA approved race cat, having said that i don't think its epa legal anyway but so far it never failed in the GTR.

At least i have a cat to show, if i was tested the stocker would magically fly in.

when I punched out a 3inch cat, it sounded terrible like id created backpressure,

got a 100cell cat from Eliteracing and a 3inch Xforce oval muffler and "boom!!" awesome raw breathing sound without the crap drone or loudness that attracts cops..

. Iv killed my second well known brand 100 cell cat in less than a couple of thousand kms. They are rubbish. They get hot, fold over and holy back pressure.

Amon please PM me the brand of cat that failed.

I would like to know this too if you don't mind, I've used magnaflow 200c metal cats on two of my cars with no problems, and they're fairly cheap on the scale of cats.

While there may be issues passing emissions with a 100c cat, I'd much rather take my chances of "maybe/maybe not" passing a test, than certainly being screwed running no cat.

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