CAT, pros and cons. At what HP will it help to take it off?

I am changing some things on my exh and am considering putting my CAT back on.

Thought it might be a good time to get some input from you'all about our favorite 'kittie'!

How much does it help to yank the CAT, Any stats on this? At what HP is it a 'for-sure' help? Thanks!

With EPA testing in some states; prob its a matter of time till i Have-To have mine on......

 

If there was nothing wrong with it, Put it back and be happy you only have that to deal with.

 

Even though we don't have emissions testing for diesels in PA, I am 99.9% certain that the cat technically needs to be in place for the annual safety inspection. A good friend of mine has an inspection station and I remember looking at his book when we picked up the 3rd gen trucks wondering about the very same question. I have my '07 scheduled to go in on Wednesday for an inspection. I will look at the latest manual he has from the state and I'll let you know for sure.

Both of ours have the cat in place. 400+K combined between the 2 of them and no issue. My memory isn't what it used to be, but I'm pretty sure that there was a lot of testing done when these truck were new that showed 500+ HP with no significant change on the dyno cat vs. no cat. I'm sure someone will chime in if I am not correct.

 

They are pretty high flowing unless they are clogged with a lot of soot . I would keep it on smog check coming to you soon thanks to the great commie state of California . It's a revenue maker for the state.

 

Don't blame every one in Commiefornia, aka Taxifornia, Mexifornia. Any state that makes it law to give illegal aliens drivers licenses can't be all that bad.(do you got a vomit bag?) I want to know how in the hell did "Governor Moonbeam" get re-elected?

 

I have plans to retire and trying some living in that same promised land of William Penn. I've been watching some politics unfold and while it's so many times better still than my nanny state, I am seeing a change from red to sort of a pale blue. It's like a disease sweeping the country. Unless you're racing or staying off road, keep it as built. You'll be glad one day.

 

Thanks for the input. I'm planning on fitting the Cat this am. I had to slit the Cat's end pipes to get it off so i plan to cut those off and add flared ends from a 4'' exh pipe i have here.
Band clamps for me! They are SOOOO nice!
I would love to hear more on the power drain [if so and at what HP] of a CAT.

I have a 'tumbling' sound that seems exh flow related that i'm trying to locate. At 1500 rpms till about 2000 or when eng noise drowns it out.
So this is why i started removing some exh peices... First my FTE 30'' resonator,= just had my flo-pro muff, sounds like a straight pipe with manners. But drone is back!
So next i switched my flo-pro and the FTE res and now i have mild drone at 1200 rpms [not bad], WOW the turbo is loud and the truck sounds like a big rig.... ===TO much noise! Prob a bit louder then just the flo-pro...
So this is why i'm going to fit the CAT just to see how it sounds and YES, i will keep it, if not on the truck, then in my work shop so at least i have clean air there! :-laf

And no; i did not find the source of the noise, just harder to hear with the exh louder...... Seems eng speed/load related. Any gear, med pedal, 1500rpms and up...

 

I would guess it might be intake related.

Nick

 

I took mine off and put on Header flanges for ease of bolting on/off when I lived in Commiefornia. I didn't notice any difference other than it was a little bit louder of a drone, but at the same time I installed a Stan's Exhaust system ( http://www.stans-headers.com/ ) so not sure if it was in fact the removal that caused this.

Truck is and will always be stock HP maybe your change would make a difference, Good luck

BIG

 

I have a 30" fte resonator installed and nothing else, and I have no drone what so ever. I installed mine right under the passengers heels where the pipe starts to straighten out, per FTE recommendation. Has a nice deep mellow tone that is not over bearing. Hope this helps.

 

In my personal testing I only noted a 4hp change at the 400 hp level and I have yet to see a plugged cat at any hp level

 

Well, i got my CAT on this morn. It def does quiet the exh more then i thought it would. Kills turbo noise as well. [i case you havnt pick this up yet, i luv turbo sound!]
Now i have a CAT that fits if/when i need it.

Thanks for the responces guys.

With just the FTE i thought the sound was plenty rowdy! Just plenty loud for me! Turbo was real clear, i do have the Tater turbo, and they love to sing!
I have mild drone at 1000-1500 Rpms, this will only be a prob if i'm tired, then sounds bother me.....

Intake related,...hmmm; I hadnt thought of this.

It is interesting how the CAT causes the exh to smell like a propane grill.......

 

I never tested like Bob did but I had read here on the TDR where there was dyno tests and they had measured 2 hp loss with the cat. Big Deal! My 5.9 runs just fine with it left on.
Is it really a cat or something else?

 

called a cat....?

 

For openers that's easy to answer.
Ahnold - "Governator" departed office leaving CA with a $27 Billion deficit.
Brown turned that around into a $2 Billion *surplus" which is projected to be $6.9 Billion in 2018, and has returned CA to
it's former rank of the 7th largest economy in *the world*.

But how did he get re-elected?
let the California Professional Firefighters answer that in their 2010 endorsement -
http://www.cpf.org/go/cpf/political-action/2010-elections/why-cpf-endorses-jerry-brown-for-governor/

Oh yeah the "Governor Moonbeam" label......"During his first term as governor, Chicago columnist Mike Royko dubbed Brown Governor Moonbeam. Why? Because Jerry Brown proposed modernizing disaster response by launching an emergency communications satellite.
It turns out that Governor Moonbeam was WAY ahead of his time".

Royko spent the remainder of his life trying to retract the spiteful (hateful?) label he attached to Brown.

Back to the OP -
As CA goes (CARB), the Feds and the EPA usually follow suit.
Expect to see the CA emissions regs in your state or part of Fed regs.
And - yeah, state revenue is another incentive to test.

However, folks "avoiding" emissions regulations (mfgrs and/or end users) are the real culprits.
You can thank the guy blowing clouds of black smoke (with his D/Max, of course) for those tests, whether you like 'em or not.

Be sure to see the SEMA discussion/s (relating to emissions) in TDR #91, pages 54-56.....in particular the conclusion/s on page 56.

And - modern cats on gas or diesel vehicles are free-flowing, not the restrictive factory items from "back when".

~

 

Thank-you!!

 

To Be truthful about the Commiefornia problem it was Gray Davis that pulled the flush handle on Commieforinans. Im sure the others were just as bad but ol Gray spent money like a drunken Sailor on leave

 

Yeah, thats my experience too.

I wonder if people follow the directions, I mounted mine the same way on my 2nd gen and the droan is gone. Actually is more pleasant than a stock 3rd gen truck at 65 mph. Its still plenty loud at idle but has lost the boomy irritating noise under load. I'm impressed with the 4"x30" FTE resonator and nothing else. It did more than I expected. Mine is just behind the transmission support, as far forward as possible with my HTT 4" down pipe.

 

Tell me how/why you like the FTE Resonator. Where is it placed? I'm thinking of getting one to eliminate the 2000 rpm drone since I replaced my CAT with the 'test pipe'.

 

FTE resonators are said to work best mounted near the down pipe. Worked for me, I just followed the install directions. On my 2wd 2nd gen it ended up directly behind the transmission support cross member, I didn't have enough clearance to attach directly to my 4" down pipe.

I really like the resonator, nice aggressive idle, its not toned down that much though. No droan in the cab windows up or down! Just an aggressive diesel tone without the headaches. Yet, under boost the exhaust is much more mild with a decent turbo whistle. I can go through town now and people don't cover their ears and cops don't look up either. Its not obnoxious like my straight pipe with the right rear turn down. Still blow the gutters clean though.