Would it be more beneficial to remove the cat or the muffler would be my other question? I am only doing one at this time. I may delete the other in the future. Thanks!

 

Deleting the cat alone won't get you much. Its the muffler thats the main restriction. Honestly for about $500 you can get a good 4" turbo back kit and be done with everything. The truck will sound awesome, you will get better response, MPG, and some power, and if you add a tuner you will be amazed at the power this engine will make. BUt be smart about every move you make with these trucks. Do a lot of research before buying anything. Ask away, were always here to help.

 

Hey Maz, I have a 4” straight back like you said. I live in MA and after 15 yrs they don’t even check emissions, I like the sound, but in a drive through or something it annoys me. It came with the SCT Tuner, it gets it👍

 

i have the stock exaust with the cat and muff taken off . the sound is great and it lets the truck breath . air in air out ...i love the sound when i step on it . i say get rid of the muff and cat

 

I deleted the factory muffler and cat and still have the factory 3.5" exhaust. 4 hours of work and the truck sounds great for a total of $75. Mine is an early 03 so it has a great whistle on cold morning starts and boy does it growl when I'm towing a 10k+ trailer up a hill!!!

 

When you guys cut out the muff and cat then replaced it with straight pipe did it kick on some service engine lights? Where did u get the pipe to weld in place?

 

What was the mpg difference with the muff and cat gone?

 

I gained exactly nothing by running a full 4" exhaust. Sounds good unlike straight piped which just produces a ton of raspy blaring at WOT. Sounds like crap if you are ever a bystander to a straight piped truck.

Jason

 

Did the muffler delete today...sounds great! Still have the stock cat. I think it will sound raspy with the cat gone too. Very impressed for stock exhaust!!

 

If you want to keep the sound good and not raspy drone keep the cat on the piping. You can knock out the inner of the cat but the open cat really does help with keeping the exhaust note sounding good. Do not slam a piece of pipe inside the cat!!
Strange but it's true, I had it both ways and it sounds so much better with the cat body in the exhaust.
If you want a raspy exhaust note eliminate the cat.
Good Luck fellas.

 

i also have been thinking about deleting my cat on my 05. i saw on a youtube video that the powerstrokehelp.com guy said that you will loose mpg if you delete the cat with out a programer, due to lose of back pressure. is that true? sounds odd. i want to do something to let it breath better and get lower egts but i dont want to to loud that my little boys cant sleep in thier car seats.

 

You wont lose MPG's, dont listen to that guy, i got rid of my cat and so no increase or decrease in MPG's. That guy is a fool. I agree with a 4 inch system, worth the money.

 

Cat delete barely helps for noise. So if you want it loud don't go that route. But you can hear the turbo breathing at idle. Your egts will go lower by removing cat than muffler too. And the install took me around 30 mins and it was $70 shipped to my door.

 

i dont want it loud, just want it to breath better and lower egts. a little sound change is no big deal. will deleting the cat change the sound any?

 

I noticed at idle you can hear the hair dryer sound. At around 1800-2000 rpm you can hear a good little whistle especially with windows down. At wide open throttle just a little more sound. But my mileage didn't change any.

 

There is a big difference in noise both at idle and WOT with my CAT in vs out. I run a MBRP 4" turbo back, and with CAT out WOT is plain loud and I think rather straight pipey. A bit too much raspyness for my personal taste.

The only downfall I have seen to running my CAT is the turbo is a lot quiter with it installed. With it out it whistles like crazy for a 07. I just reinstalled my cat and I like the sound of it WOT, once above 3000 RPM it sounds like a big block gasser.

I also didn't notice any real change in EGTs, maybe 100 at WOT at the end of 1/4 mile but normal cruising and idle EGTs have remained the same.

Dik

 

can you tell any differance in fuel milage

 

Not really, I seem to get 16 highway and less in town. Combined is about 13 and I make sure my turbo vanes are not going to stick :thumb:

 

i deleted the cat on my 2003 6.0 and now the truck stalled out after driving for about 1 mile and will not start any suggestions.

 

Put fuel in it.

Deleting the CAT has nothing to do with your stall, unless you did something really wrong.

 

I have done the cat and muffler delete pipes. Absolutely love it. Very happy with the performance, sound and cost. About 70 bucks. I have had this set up for about 90,000 miles. Very happy.
Also with living in California the cat delete pipe super easy and convenient.

Don't gut you catalytic converter. Just get the delete pipe.

 

If you have to deal with a smog program then you are going to need to keep the cat in the exhaust. You do not need the muffler since it is not a emissions device. But the down pipe and cat must remain stock, after the cat converter you can do whatever you wish. But no 4" down pipe or any changes from the cat to the engine.
I can assure you though the open can of the cat smoothes out the exhaust note a ton. I ran my truck with straight pipe all the way back and it was raspy as hell. There was a drone in the exhaust, my old truck had a empty cat and sounded much better than my straight pipe system. So I took the cat from this truck and knocked out the honeycomb and welded 4" pipes to it and placed in the stock spot.
As soon as it was installed the exhaust drone was gone. Strange that a open body has that affect on the exhaust sound but I assure you that it does.
If you want a loud growl out of your truck straight pipe it all the way. If you want to keep it a bit smoother and quieter put the cat body back in.
As far as power gains without the cat you won't get any. The one gain you will get from removing the cat is 100* lower EGT. Mileage will also be the same, the cat does not change the power or mileage. But it does change the sound of the exhaust for sure.
I also installed a Corsa muffler on my truck to tone it down a bit more. It's a straight through design and uses new technology on sound waves. Pretty cool muffler really all stainless steel too btw no packing of any sort.

Good Luck on your truck..............

 

It will be very loud going with a full straight pipe system.
Thus is my I kept the stock system and did the delete pipes. Not as crazy loud.

 

Just gone done putting 4in turbo back on my 03. 10x better more responsive. MBRP as well with cat delete. I like the mbrp mufflers.

 

you won't see a difference with this cat
I used to run smokey tunes and then a hollow cat never any perceivable difference

so just run a clean tune like everyone should now days , and you won't see " extra smoke" without a cat