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Removing Catalyic; What Happens?

Old 04-11-2017, 09:01 AM
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Removing Catalyic; What Happens?

I know the info is probably posted somewhere, but not sure how to search for exactly what I'm asking.

05; 2500; 4x4; Laramie.

Question: Will I create any mechanical/engine problems by removing the Cat & Muffler? and going with a straight pipe?

I believe Texas emission laws / inspections are different than California, so shouldn't be a "legal" problem....and no intention to ever cross California borders...

Question: If I do remove the Cat/muffler, will I see any positive performance changes? (MPG? power?)

thanks!
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Old 04-11-2017, 06:50 PM
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The cat has next to no flow restriction. It is a violation of federal law to remove it. Just a better flowing muffler with the cat will yield a throaty sound and will assure you will have some hearing left in years to come.
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Old 04-11-2017, 09:43 PM
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Originally Posted by Danderson View Post
The cat has next to no flow restriction. It is a violation of federal law to remove it. Just a better flowing muffler with the cat will yield a throaty sound and will assure you will have some hearing left in years to come.
I agree. Went down the same road at one time, and gained absolutely nothing by removing a perfectly good cat. Made a noticeable difference though by swapping the factory muffler for a better flowing one.
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Old 04-12-2017, 10:06 AM
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Originally Posted by torquefan View Post
I agree. Went down the same road at one time,....noticeable difference by swapping the factory muffler for a better flowing one.
Thanks! Ref the muffler, which one did you go with, and ref "noticeable difference"--was "difference" in performance or simply sound?

Tks D
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Old 04-12-2017, 09:59 PM
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Originally Posted by danalex View Post
Thanks! Ref the muffler, which one did you go with, and ref "noticeable difference"--was "difference" in performance or simply sound?

Tks D
I went with the BD muffler and tailpipe. Noticed a faster spoolup right away. Not a huge difference of course, but I was impressed (and surprised) that I could actually feel a change.

https://www.dieselperformance.com/page/homepage
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Old 04-28-2017, 02:00 PM
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My 04 did not come with a cat, so I can`t comment on the difference. BUT I can`t / won`t buy the" not restrictive" CRAP. Just cut the cat apart and you can`t help but notice that it has gotta be restrictive.
One of the main reason I shall keep my 04

By some posts I could gain mpg with a cat-----I don`t think so Tim.
Removing the cat is not legal-BUT any "greaser" knows how much better the engine will breathe.
I don`t wish to step on toes but we still have(for now) the 1st amendment.
Hell, why don`t we just drive a prius..............................
Better be careful as I know "big brother " and all his "greenies " may be monitoring!
Just my.02
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Old 04-28-2017, 09:34 PM
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Originally Posted by sojoe View Post
My 04 did not come with a cat, so I can`t comment on the difference. BUT I can`t / won`t buy the" not restrictive" CRAP. Just cut the cat apart and you can`t help but notice that it has gotta be restrictive.
One of the main reason I shall keep my 04

By some posts I could gain mpg with a cat-----I don`t think so Tim.
Removing the cat is not legal-BUT any "greaser" knows how much better the engine will breathe.
I don`t wish to step on toes but we still have(for now) the 1st amendment.
Hell, why don`t we just drive a prius..............................
Better be careful as I know "big brother " and all his "greenies " may be monitoring!
Just my.02
I have measured back pressure with a gauge, on many engines (gasoline) that I suspected of having a plugged cat. If the cat is working normally, I couldn't say there was any measurable restriction, more than what a factory exhaust would provide. Granted, I wasn't able to measure while the engine was under a heavy load, but on most engines at OEM power levels, I don't think it makes a difference. Add 50 or 100 HP to that engine and that cat probably becomes restrictive; as does the muffler.
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Old 04-28-2017, 11:20 PM
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At least two guys on the TDR did dyno tests before/after cat removal. Removal of the cat yielded 4-6 rwhp per 400 rwhp made.
I wish mine didn't have one but the cat's not the restriction. The stock muffler is.
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Old 04-29-2017, 09:36 AM
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A number a guys have seen a slight fuel millage drop when removing their cat. 1-slightly over 1 MPG.
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Old 04-30-2017, 09:30 PM
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Golly-I think I will put a cat anf factory exh on-Happy daze and at least 1.5 MPG more.....................
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Old 04-30-2017, 09:47 PM
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Originally Posted by sojoe View Post
Golly-I think I will put a cat anf factory exh on-Happy daze and at least 1.5 MPG more.....................
Keep us informed.
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Old 05-01-2017, 12:21 AM
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Originally Posted by sojoe View Post
Golly-I think I will put a cat anf factory exh on-Happy daze and at least 1.5 MPG more.....................
maybe you should do some research about these trucks and the cat. Then you'll understand there stud.
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Old 05-02-2017, 11:53 AM
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Thank you for the upgrade to "stud" status...................[duhhh
So I will remove the free wheeling hubs also + the grid heater delete + the smarty + the magnaflow exh AND keep the ehx brake engaged to increase back pressure and be good to go.......................................
Da**, I wasted all that money when all I had to do was put a cat on.
Thanks for the input
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Old 05-02-2017, 04:08 PM
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Originally Posted by sojoe View Post
Thank you for the upgrade to "stud" status...................[duhhh
So I will remove the free wheeling hubs also + the grid heater delete + the smarty + the magnaflow exh AND keep the ehx brake engaged to increase back pressure and be good to go.......................................
Da**, I wasted all that money when all I had to do was put a cat on.
Thanks for the input
There 'ya go.
I have a Shuttleworth diesel truck muffler out of Canada. The last one yielded 11 yrs. They're expensive but a quality unit.
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Old 05-02-2017, 10:38 PM
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Originally Posted by sojoe View Post
Thank you for the upgrade to "stud" status...................[duhhh
So I will remove the free wheeling hubs also + the grid heater delete + the smarty + the magnaflow exh AND keep the ehx brake engaged to increase back pressure and be good to go.......................................
Da**, I wasted all that money when all I had to do was put a cat on.
Thanks for the input
grid heater delete and the magnaflow was a waste of money, you are correct there stud. But that still has nothing to do with the cat.
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