It will help flow, it's breathing through two porous rocks on each bank right now. If you would have went with a Diablo Sport tuner either you would have had the option to disable the rear O2 sensors or Lew deffinatley ccould have. Shorty headers and a cat delete is a pretty good upgrade over stock if long tubes are out of the question.

 

OK, I like the performance side. Will the 02 sensors cause issues if I don't get it re-tuned by Diablo for a while? I'd love to get one of their programmers and have a custom tune done, but that's not in the budget right now.

 

You will have your check engine light on all the time since the rear O2 sensor reading will be out of spec. I know of people that drive like that but I am not sure if there is any long term by doing this, i.e. the truck adjusts its fuel to try and compensate for the improper reading. I am sure Lew or one of our ASE mech's can help a little more there. By the way, I am pretty sure that other tuners can do this as well and I know Black Bear is more than capable, I just know you were interested in the inTune.

 

let me speak from experience.

i currently have no cats on my 5.3. i still get the same mileage as before and you can smell my truck a mile away. also at 180,ooo miles when i took the stock cats off, there was was zero build up inside and i could see daylight through them. the inside kinda looks like the screen on our map sensor just a bit tighter.

i recently talked to one of the exhaust experts at the college (who writes for a certain rod mag). and he explained also that now days with the cats being as good as they are at "filtering/cleaning" the exhaust emissions as they are, engine manufactures build engines that run dirtier than most of the engines built back in the 60's. hence the reason my truck smells stronger than my buddies 67 nova.

on a side note the o2 sensors will not do anything but set a SES light. the down stream o2 sensors only monitor the efficiency of the cats as per ob2 requirements. you can use a hollowed out sparkplug defouler to get rid of the light 19mm i want to say.

 

Defouler's were how they got rid of the lights on my Civic Si before th Hondata tuning software came about. I have always figured it would do the same thing on our trucks, you would just need two of them in the correct size.

 

FWIW, if low end torque is a factor for you (towing, hauling at lower RPM) the elimination of the back pressure commonly caused by a CAT may cause more harm than good. Again, FWIW.

 

I tend to disagree with the whole "backpressure saves torque" argument, so this is a good way to find out if I'm right ! The 6.0 makes peak torque and power really high in the RPM band, anyway; plus I've got a 4.10 rear axle that helps a lot.

 

I tend to disagree with the whole "backpressure saves torque" argument, so this is a good way to find out if I'm right ! The 6.0 makes peak torque and power really high in the RPM band, anyway; plus I've got a 4.10 rear axle that helps a lot.

Fair enough, just for your viewing entertainment take a peak at what Arron Johnson has to say. This dude has built more engines than likely most of us will ever touch.

How can I turn my late model GM truck into a power house?

What is the difference between horsepower and torque?

 

Good info. I've heard "experts" from both sides of the argument... there's only one way to settle this. Hopefully when I get some spare time, I can look into finding a shop that can do it for a good price.

 

Good info. I've heard "experts" from both sides of the argument... there's only one way to settle this. Hopefully when I get some spare time, I can look into finding a shop that can do it for a good price.

you might have to cut the cats out yourself being that its against federal law to remove them.
i did it, i wouldn't do it again.

 

Why wouldn't you do it again? And yes, I know Uncle Sam wouldn't be happy if I cut them out.

 

Another (somewhat off topic) idea.
As a business owner, you probably don't want to be "rumbling" up to a house to do lawn maintenance. Or, really bringing the noise when you are plowing? What will the noise level be when you do this mod? The quieter the better, for your business....

 

That's a good point, Eric. I've thought a lot about that... the truck is just loud enough to be heard, but not loud enough for my tastes . Then again, I don't want to rattle my customer's windows. Does anyone know what a cat delete would do to the sound?

 

the reasons i wouldnt do it again are that
no mpg gain/improment
still takes as much pedal to break the tires loose as before,
it made my flowmaster 40 sound like it fell off
im too lazy to fix the ses light
my truck smells like shes running way rich. i know shes not because i get 15mpg mostly city driving with 4:10 gears and crapy california hippy gas.

im actually thinking about putting them back on when i save up for a custom made system.

 

Huh. Well, maybe I won't do it, then! Thanks for the heads up... I didn't even think about the smell.
I guess I'll just have to settle for some nice headers and a custom tune .

 

Go for some Stainless Works headers with cats. Those things are sick but you will pay for them. I am starting to lean towards them and their cat back ($2,500 for the whole set up! $1,500 for the headers and 930 for the cat back).

 

$2500? That's about half the price of a supercharger :shock:. I'm fairly happy with my current setup, so I'll probably just get the long-tube headers, and call it a day (unless I stop using this truck for work, and then I can really go wild on it ).

 

The only good thing is you can buy it in two parts spreading out the cost. I was thinking about getting the exhaust and then getting the headers down the road.

 

True, but the 6.0 has at least 3" piping (I know from the muffler on out, it's 3.5"). That seems big enough to handle a LOT of exhaust gases. Ideally, I'd run long-tube headers, to high-flow cats, to an x-pipe, and then duals out the back. But, that's just way outta my range, and unless I'm putting the truck on the track, long-tube headers should be sufficient with the current setup. Thanks for the advice though.

 

I know this post is old but if it will help anyone in the future listen carefully...LEAVE THEM ALONE...I cut mine out of a 4.8 vortex and it did absolutely nothing but cost me more money...wish I would have never touched them...but I'm just one guy...im sure someone will argue with me...but he don't have to drive my loud smelling truck