Exhaust question

[Jim Ross]

On our '07 with 5. 9, in the exhaust system there are 2 items besides the pipe.

1 is a muffler, but what is the short fat round canister that is located between the turbo and the muffler?

Is it a resonator or is it a catalytic converter?

On our '01, I have just 4" pipe with no muffler or anything... ... I don't mind the tone and getting rid of the muffler and resonator on this truck lowered my egt's by 125 degrees. I am thinking of doing the same thing to our '07.

Anyone have experience with the late 5. 9's?

 

[SierraRam]

That is the CAT.



It will be loud straight piped, with some drone but your EGT's will drop. I currently run the 5" MBRP turbo back and love the sound. If your state starts inspections you will need the CAT back in place to pass.

 

[Jim Ross]

What could I expect by just using a "muffler elimination" pipe?

 

[CurtLee]

I read somewhere on here that on some 06 and newer trucks had resonators installed. That's not something i know about. I went to dual exhaust on my truck and when I order the pipes they didn't have any mufflers in stock so i went straight pipe cat back. After that the truck was LOUD and it sounded good.



Unfortunately Utah law states you have to have a muffler on your vehicle so when I got it inspected in February they wouldn't pass it so I had to get a muffler installed. Check your state laws and if they require a muffler keep the stock piece and put it back on for inspection. The muffler I went with is a 14" magnaflow.



Sorry for the long winded post.

 

[macdaddy]

I believe you have to pass smog in your state, If so and you want to mess with the kitty, remove the guts and reinstall. This will allow you to pass visual inspection. It sounds nice with a regular muff,,



Mac

 

[HBarlow]

I removed the muffler and used a section of straight pipe but left the catalytic converter in place on my '06. It was a little loud outside the truck but not inside and I did not have the exhaust drone some complain about. I liked the sound and never had any trouble with law enforcement or DOT types while crossing scales, etc. as an RV transporter. I liked it and would have done the same with my '08 but the muffler shop owner told me he had already done a new at the time Dodge and it made no noticeable difference so I left it unmolested.

 

[Jim Ross]

Harvey, did you notice any drop in your egt's after removing the muffler?

 

[SierraRam]

Believe it or not in California the turbo counts as a muffler. I did run my truck with just the muffler elimination pipe and liked the sound. I didn't notice any significant EGT drop. When I went to the Smarty I wanted to open it up and went to the 5" turbo back. I did notice lower egt's 50-100 degrees but it is louder and has a lower exhaust note.



I had to make a flanged adapter for the CAT so I can install it when theinspection is due.

 

[HBarlow]

Harvey, did you notice any drop in your egt's after removing the muffler?

No, I didn't notice any reduction. Theoretically I would expect a small reduction due to slightly reduced back pressure but I didn't really observe one. I just liked hearing the mighty Cummins doing it's work.

 

[Jim Ross]

OK, after a month or more of driving after removing the muffler, I can't say that I have noticed and reduction in EGT... ... ... "maybe" a tiny bit faster in cooling down, but if so only by a small amount.
I do enjoy the tone with no muffler and do not find it objectionable in the least.
A couple of weeks ago, I tried the Smarty Jr. I have not done enough "testing" yet, but it appears that with it set on the economy mode as follows: #4 timing setting (the most advanced), the "stock" torque setting, and the #75 power level... ... . It appears I have gained approx. 1. 5 mpg while towing our 27ft 5th wheel trailer and lower egt's while towing.
I am thinking of keeping everything the same except for changing the torque level to "default" from "stock" to see what difference that makes.
Any thoughts?