04.5 Exhaust questions

[grfraz]

I want to change out my exhaust, at least my muffler and possibly the CAT. I was under the truck the other day looking, and the exhaust pipes aren't that small in the bends, unlike a gasser that has 1. 5" or 2" exhaust pipes. So, my questions are;



1) do I really need a complete system from turbo back?

2) what benefit if any does the Aeroturbine provide?

3) what othe resonator options do I have?

4) is the MBRP spiral flow muffler as good as the adds say?

5) has anyone else just changed the muffler and how is your performance?

6) if I just change the muffler to a straight through design, can I use GENO'S muffler elimination pipe to get the exhaust back into its factory position?



That is enough for now,

Thanks



Gene

 

[EEngel]

Cat

Gene,



Somebody stold my cat off the truck pretty early in it's life. I did not notice any EGT change and I did not notice any power change. Just a little more noise.



Just my $0. 02... .

 

[jwilliams3]

If you order exhaust for the 04. 5 ask for the 03-04.

The mfg's are getting scared/cheap and only offering cat back for the 04. 5-05's.

 

[nickleinonen]

If you order exhaust for the 04. 5 ask for the 03-04.

The mfg's are getting scared/cheap and only offering cat back for the 04. 5-05's.

if you do that, you'll get a downpipe that has no use to you as the 600's have a full 4" downpipe & cast elbow... all you'll need is a test pipe piece to bypass the cat and 04. 5/05 exhaust system will work well...

 

[jwilliams3]

Nickle,

Good idea.

 

[tdecosta]

Upgrading the exhaust

grfraz,

getting an exhaust system right for you can be a challenge. You may not be able to see and hear all of the products you would like to. Some manufacturers and some distributors provide sound files, which may or may not help you to make a decision. Another issue is "drone" which many find annoying. I found conflicting answers from sellers and owners in regard to which systems provided good flow and sound without producing an in-cab droning sound.

A cat-back system will cost less, and work well under most circumstances. Back pressure is not caused by the cat as much as the stock muffler on your 04. 5. Like EEngel above, mine was also stolen, but in contrast consistently showed 50 to 75 degrees decrease in EGT's, from highway cruising to WOT. I installed MBRP cat back system, and like the sound. I do not notice in cab drone, but will wait to see what passengers have to say. I did not notice an abvious increase in performance.

If you are anticipating upgrading your Holset, then this will affect you decision as well, since some have larger flanges (5"). Good luck, let us kwon what you do.

 

[RonsRig]

I went to my local Cummins dealer and bought a Nelson 51" muffler and had a local muffler shop install it upon recommendation from one of the Cummins parts guys. It is 4" straight through and it growles, but not too loud. For less than $120 total, I am happy with it.

 

[grfraz]

Great ideas, thanks. I know there's more opinions on this subject.



You are right jwilliams3 I haven't found many that doesn't say that the system is not a cat back, but the manufacturers aren't getting cheap, they are selling less for the same or more.

 

[JohnnyH]

I went to my local Cummins dealer and bought a Nelson 51" muffler and had a local muffler shop install it upon recommendation from one of the Cummins parts guys. It is 4" straight through and it growles, but not too loud. For less than $120 total, I am happy with it.

Was the 51" nelson a bolt on application, or did you have to modify anything. Also does it fit with the Cat in place. I plan on leaving the Cat in place for emmisions.



John

 

[RonsRig]

JohnnyH,

The muffler shop welded it into place because it doesn't come with hangers. The welder made a couple to fit the stock hangers but he eliminated one hanger. It is plenty rigid and I haven't had any problems with it. It is longer than the stock muffler and there is just enough room to get it in there between the cat and the bend that starts up over the axel. It hangs down a little in the front, not bad. If you want a bolt on application, do the cat back thing. I did this because I have a 4" systerm all the way through and it was cheap. Bombing on a budget.



Ron