Cutting the cat

ramthis9501 · Oct 2, 2012

I'm getting the exhaust redone sometime next week and I'm really thinking about getting the muffler shop to just go ahead and cut the cat while their at it. I've heard some say that it will be negative on performance and others tell me it'll be fine.

Can someone please explain in detail what cutting it off will do?

In my mind, it will help it flow alot better since the cat is already pretty restrictive imo. The sound of the exhaust sounded the exact same as it does now when I tested it awhile back coming straight out of the cat.

So convince me on why I should or why I shouldn't do this.

S2kiHemi · Oct 2, 2012

Smell, won't pass inspection, won't really notice any difference.

TheSatinPumpkin · Oct 2, 2012

Also you will get codes.

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ramthis9501 · Oct 2, 2012

No inspection in Oklahoma so don't have to worry about that and I wouldn't mind the light on the dashboard.

v8only · Oct 2, 2012

New cats flow real well...u will see no to very little sotp difference in power...itll smell bad..real bad

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TheSatinPumpkin · Oct 2, 2012

Nice.

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ramthis9501 · Oct 2, 2012

So there won't be any power loss?

SmokedRam · Oct 2, 2012

I don't know of any shop that will cut the cats off for you. You'd have to do it yourself. At least down here anyway.

TexasRammer · Oct 2, 2012

I think youll be fine as long as you run a good muffler with it

Sagebrush2500 · Oct 2, 2012

Don't the cats have the O2 sensors that tell the truck the air/fuel mix? I can't imagine the truck running correct without the O2 sensors giving feedback.

I could be wrong. Just doesn't seem as simple as chopping off the cats on pre-EFI vehicles

smiley · Oct 2, 2012

They won't do it for you as they would be facing HUGE fines I believe in six digits if caught and it would gain you nothing except very smelly exhaust and a lot of noise and check engine light.

$miley

SmokedRam · Oct 2, 2012

smiley3303 said:
They won't do it for you as they would e facing HUGE fines I believe in six digits if caught and it would gain you nothing except very smelly exhaust and a lot of noise and check engine light.

$miley

Exactly...even though you don't have inspections, CATS are federally mandated...any reputable shop will only remove your CATS to install new ones.

ramthis9501 · Oct 2, 2012

Hm... Maybe I should just get them to do the muffler, then I'll see how I like the sound and performace. If I'm not happy with it, then I'll just cut it off myself. Thanks guys.

Okiespaniel · Oct 2, 2012

smiley3303 said:
They won't do it for you as they would e facing HUGE fines I believe in six digits if caught and it would gain you nothing except very smelly exhaust and a lot of noise and check engine light.

$miley

SmokedRam said:
Exactly...even though you don't have inspections, CATS are federally mandated...any reputable shop will only remove your CATS to install new ones.

Agreed...you'll not find a shop to do it.

Your truck should have a 2 into 1 lead pipes into a 3.5 inch pipe into the converter. That's what my truck has. Your improved converter doesn't have the problems with clogging the pre '99 converters had. It probably flows as well as many aftermarket cats.

I believe allowing your check engine light to stay on because your system is ghetto rigged sounds pretty...well...stoopit. The fact that your O2 sensors don't function properly affects other tuning factors in your pcm. Thats why most people that do this notice a HUGE low end loss and other issues. If you are going to run a true dual off road system with some kind of O2 replacement module then you might be notice some improvement.

smiley · Oct 2, 2012

To clarify this is different than a diesel and may be why you asked. The cat has a place. The system is needed to work correctly now on a gas engine because it is designed around it and causes so many issues if removed. On a diesel it is opposite and the DPF and regen items wreck the engine and cause nearly all problems and is an add on they are forced to put on. Dodge and Cummins know this but have no choice either they choke it with this crap or they stop selling HD diesels all together.

ramthis9501 · Oct 2, 2012

Makes more sense now, I'll just leave it on for time being and see how I like it with the new exhaust.

Also, I just realized that my dad's diesel never threw a code after we straight piped it... Guess diesel pcms like it more then gas right?

Needaram · Oct 3, 2012

Get a highflow

Texas Hemi · Oct 3, 2012

My cat was going bad on the '98 (it had a weird rattling noise and very poor throttle response) so I took it to my muffler guy. I've known the guy for a long time and he's done some awesome exhaust work for me in the past. He agreed to install a "high flow cat" which meant he took mine off, gutted it, and welded it back on. No CEL, no problems at inspection (it looks like I have a cat, plus they don't check emissions here) and it ran better than the day I got it. Way louder though, I ended up having to reroute my exhaust later on to move it all back a little further.

Bigtman07 · Oct 3, 2012

Hey Colton remember when I came through OK and we met up for dinner? My truck still has the cat but is straight pipe. I would look into that too. Not too loud, not a bad crackle, no lights, no power change, good sound. Just some extra food for thought. Not to mention you got to hear it in person.

ramthis9501 · Oct 3, 2012

Yeah yours did sound pretty good Tony, but I'm really set on getting an AT2525 for mine.

I'll ask the guy at the muffler shop about gutting the cat when I go up there. Thanks guys.

Cutting the cat

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