Turbo back / Cat back question (for 'o3/'o4,'o4.5 owners)

[DZink24]

I am in search for an aftermarket exhaust for my 305 HP 'o4. As I look at all the companies on line, I see the terminology of tubo back and cat back exhausts systems. Do these mean what I think they mean? If so, the 'o3/'o4 models cannot have a cat back, right? Because there was not one there to begin with. The 'o4 model year is a tricky one to shop for, because rarely are the exhausts differentiated, between '04 and 'o4. 5, 3. 5" turbo to muffler, 4" muff to tailpipe, and the 325 HP motors are 4" "turbo back". Most of (if not all) the exhausts I see advertised call the "'o4" models 4" turbo back, which mine is not. Should owners of a 305 HP just use the 2003 classification to be safe? By the way- I am looking for an relatively inexpensive flow thru system, (muffler or full exhaust), the salt in the winter will tear an expensive one to shreds.

 

[JHardwick]

If you buy a 4" elbow and down pipe, there is very little to replace to connect to the 4" tailpipe ... ... ... . which is a very nice piece.

 

[R_Painter]

I thought the 04. 5 was th efirst year for a cat in a cummins ?? i like my flo-pro 5" pipe

 

[JThiessen]

You have a good understanding of what you are looking for. Definitley get turbo back, and you could also verify that it includes a new turbo elbow (changes the outlet to 4"). I believe some cheaper systems just give you a necked down pipe instead of a replacement outlet.

Yes, one that includes 03 will fit yours.

Also, make sure you get one that fits your bed length (I had a snafu with my last one on that).

Some companies also sell their turbo back systems for all model years (03-07). Not much has changed with the exception of the outlet and the downpipe.

 

[LesStallings]

Some of us 04 guys have purchased the 04. 5 cast elbow (from Dodge or from someone that has installed an exhaust brake on their 04. 5) and the 04. 5 downpipe. Next, since you now have the equivalent front part of the 04. 5 system, you will need a Cat elimination pipe, since you don't have or are required to have a cat converter. Once you do that, any 04. 5 system will fit.



Since the tailpipe on 04s is already 4", you can buy the MBRP muffler kit and install it, replacing the stock muffler. You will need to cut off a short section of the tailpipe where it connects to the muffler, but that is an easy job. Get stainless steel 4" band clamps and you are set.



No welding required. The sound is throatier below 1,500 RPM but only slightly louder cruising at 70 MPH. You can see right through the MBRP muffler, end to end. Very low restriction...

 

[Morin - MBRP]

You do have a very good understanding of your vehicle. The '04 usually has a 3. 5" downpipe compared to the 4" downpipe on the '04. 5. Usually the '04. 5 will have the cat as well. Our systems come with one classification for the

'03-'04 and another for the '04. 5-'07. One way to tell for sure which you have is to look at the sticker under the valve cover - 305 is an '04, 325 is an '04. 5.

If you're running through a lot of salt/sand/snow, you should maybe consider going with a T304 stainless system..... it'll stand up to the harsher elements.

 

[JHardwick]

What ever you do, don't put a Banks Monster Muffler on it ... ..... unless you want it as quiet as factory #@$%!



I had to do something about the 2200-2500 drone that was ear splitting. I had to drive around it if I was in ear shot of a customer. Also, I have seen people I was passing, raise their window, cover their ear etc. It wouldn't have been so bad, except it was so high pitched! I'm surprised it never busted a window in the driver side door of cars I was passing.



The best sounding exhaust I ever had on this truck was the gutted OE muffler ... ... ... hands down. No drone whatsoever, and plenty of deep grunt without being obnoxious.



I had intentions of going 4" off the turbo and making the 5" tip longer trying to "tune" it to a deeper growl ... ... ... ..... alas, when I got to the shop, my buddy (diesel machanic) said, go ahead and complain, I stuck a muffler on it. :-{} He happened to have a Banks muffler with a few hundred miles on it laying in the corner



This thing is quiet! It's only a shorty, straight through type of deal, but it sure tamed it down! I can't even imagine leaving a cat on a newer truck, but doing a straight through muffler ... ... . has to be a waste of $$.