That's exactly what I just though. Lol

 

For the sack of argument lets say I never have to worry about the emissions control cops, never, or am prepared to fix what ever needs to be fixed to get it passed if they ever do find it safe to come to my neck of the woods. First would it be a a good mod to gut the cat on a stock system? Not talking about going with a hole new 4" exhaust system with a cat delete and a better flow muffle because this is where I am eventually going after I get some other mods paid for first. Just want to know if the time is worth it. Basically if I can drop my EGT's by 100 degrees on the high end or get the EGT's to drop a little faster before I shut it down it would be worth it. Right now I have to keep my eye on the EGT while I am towing over 10,000 on steep grades don't like to put it much over 1300. Even though this may not be a high payoff Mod it's something to do while drinking a few beers but if its not worth the effort I will take care of some Honey do's.

 

What tunes are you running while towing that weight? What I have seen and heard from comments made by users is that a 3" straight pipe is a improvement from stock and comparible to a 4" system. So basically ditch the cat and muff be cause both will give the biggest gain.

 

The tunes will be future SCT tunes because of the planned EGR delete on the MY 2005. But the 3 1/2 down pipe and 4" back with a cat delete and high flow muffle will be in my future before the EGR delete and the SCT tunes. I have to keep the muffle for the neighbors and the wife. Anyway this won't probably come until the end of the summer. Just thinking about what I can do cheap before the summer heat and much towing I will see over the next 2 of 3 months. Thanks

 

Get a muff delete pipe and see how loud it is. I've heard a few 6.0's that were not to loud for a straight pipe. I will probably do a muff delete at some point but I want to be able to put it back in if I needed to later.

 

Man, I have sompletely stock exhaust with muffler and cat intact, and I can still hear my '03 turbo at idle

 

I can hear the turbo at idle out side of the truck. It is not that loud though pretty faint.

 

Alot of folks remove thier muffler. That is actually pretty common with guys on this site. I went with an MBRP exhaust.

If you dont immisions test where you are kill the CAT

 

I can hear my turbo inside my truck when idling, when i pass buildings with my windows down at about 2k rpm's, my turbo makes my ears my hurt, i dont know how to describe how loud it is, the video doesnt even do justice, i need to record a better one.

 

Since I am going with a 4" exhaust a little later I didn't want to waste the money on a cat delete pipe or a pipe to delete the muffler but looks like they are around 50 bucks so thinking I will get one and save the cat. Maybe I can sell it later to someone that thought the emission control cops would never come but did Any thing that will stand a chance of dropping my egt's down a little over some expected heavy hauling this summer would probably be a good thing.

 

Yeah I can hear mine inside the truck at idle. I can't wait to get my 4" straight pipe installed, I do believe without the CAT and Muffler my turbo is gonna scream!!! It is already pretty loud.

I'll make sure to post a video

 

This is all great stuff but back to my original question: Cat delete= power; mpg; lower egt.
From what I'm seeingower gain - barely measurable on a stock system; mpg gain-not worth the effort; lower EGT- the winner.
Even a 100 degree drop from what I've read can make the difference between EGR system failure or not when towing/summer heat.
Am also correct that the factory muffler is the bigger 'plugger' and that either a strait pipe (if I can handle the noise) or a high-flow muff will do more good.
At present I am all stock (2005; 62K) and would prefer to keep the cat (because my kids need to breath on this planet after I'm gone) and try a back of system mod.
These are super clean engines to start with so i am still a bit hung up on the need for a cat. My fuel is also very good up here in Canada (Shell V Power).
Does anybody know how much the cat actually cleans up the exhaust and once they 'plug up' are they designed to just become a flow through pipe anyway???
Thanks for all the input to date!

 

Seems I stumped the collective.....let me rephrase my main question:
compared to the old 7.3 that belched blake smoke and the 6.0 that looks clean out the tail pipe-will removing the cat make it puff black?

 

Thanks for all the input to date![/quote]

The cat does not become a flow through pipe, It has two screens in it that has alot of small holes in it.

My truck is straighted piped, the only real differance is the sound and lower egts. No smoke at all.

 

I have a pretty good way to settle this question. My neighbor has an '05 just like mine. We both have 4" MBRP exhausts. I still have my factory cat in mine, he does not. I have the 3.5" downpipe also. The only thing stock on my exhaust is the cat. His truck has a significantly louder whistle than mine. Mine has a loud whistle too, just not as loud. If I pull a steep grade towing 10k plus I never break 1100 degrees. EVER. I was told by my Ford tech that a stock cat flows 2% less than a straight pipe. There is some required backpressure to stop the turbo from overboosting. The stock turbo is meant to peak at 27lbs of boost. Anything over that can cause problems. I get good enough mpg's to impress most people. 17 on average, 19 if I burn the tank on highway in one non stop trip. Good enough for me, beats the 14 I was getting when I bought the truck. I think it is really just a personal preference, if you want more noise get rid of the cat. I also left my cat in to protect myself from Ford if I had any emissions warranty claims. Just something to think about.