i did that to my 97 ford expeditions. i cut open the cat and took out all the cones inside, welded it back together. u know what it has more power now and saves a lot gas too, sounds great too......

 

No it won't. The reason it makes the light come on, is that the rear O2 sensors don't detect a decrease in emmissions as compared to the front set. It has nothing to do with running rich, or losing power, or decreasing gas mileage. All the light is saying is, "hey, your cats aren't working!!"

A mil eliminator tells the computer that the emissions level is low (after the cats), and so the computer doesn't suspect a thing, and your "check engine" light will not come on.

Now, you have to leave your front O2 sensors alone. They determine A/F mixtures. But they come before the cats, so......

But, I'll say it again, there's NO reason to cut them off. You're just wasting your time, unless you want it louder.

 

I cut the cats out of my 302 and ran true duals in place of the 2 cats and the single exhaust. i got lucky with the o2 sensor cause it's threaded into a balance pipe (i guess that's what it is) about 8 inches before the first cat. my check engine light has never come on either and I could deffinatly tell a difference in power and fuel mileage but my truck is a 93 and i imagion they were getting pretty clogged. I'd say go ahead and cut 'em out and you won't have to worry about doing it later. flex pipe works great for bypassing like that. cheap too. plus, super 40's on v6's sound real nice without those cats.

 

E-Bay.
I bought my Magnaflow high-flow cats for $60 each.

 

Only do it for the noise. The power is just an illusion. Just like when you put em back on itll seem like its under less strain and much quicker. Done this and that, trust me. Only thing you'll do is you will have an annoying and now useless for other monitoring systems light on.

How could it have less emmisons and better gas milage and more power???? WTF? Thats the most bull**it thing ive heard. Every company didnt get together and say lets throw one of these on just for the hell of it. It'll be bad in every way but seems like a good idea. no.

Cats reduce emmsions period.

And in my opionion there is no such thing as a high flow cat. Its the same stuff in there.

http://auto.howstuffworks.com/catalytic-converter2.htm


Maybe you shoulda bought a v8 if you wanted more power. Think about that.

 

I still believe no cats is better flow... right? not 60 dollars spent on magnaflow.

Just depends where you from & if you can actually get away with it.

 

 

An empty pipe will always flow better than one with a honeycomb substrate in it.

That being said, the question becomes "how much is the flow reduced with a cat?"

The answer, IMHO, is minimal.

But I live in CA so I have to run cats.
Of course, I've only got two out of the original 4...and I still passed the smog sniffer

 

I didnt say it wouldn't flow better but i dont think the difference is anything that will even be noticable on our engines. Plus i know some backpressure is good. makes you have low end torque (i heard). But yes the pipe will probably be fine.

I just done believe that there will be any notice of power nor fuel ecomony and i know it wont lower your emissions.

Hell im only 19 ive done all this **** before, just as recent as a year and a half ago. Its fun as hell making ricers and people who think their stereo systems are all that roll their windows up. Then race em and they find out an old 1982 rusting green Chevrolet pickup wasted their honda with the fartcan exhaust and neon ground lights.

Probably the only reason i havent touched the exhuast on this truck is cuz i took out a loan when i bought it to try and start building a little credit. So i haven't paid it off yet. Well that and im trying to be nicer to it. I know if i maintain it and treat it well now it'll be nice to me much longer down the road.

And i agree that the flow difference is minimal w/out cats.

 

What kind of gaines can I get by hollowing out my cats on my 03 4.2L w/77 serries and 40 flowmaster.

 

A noise gain.