SHARPMACHINE

Hello,

Probably a newbie question, but... I just got a 2003 HO and am looking to upgrade the exhaust. A friend of mine has a 4" kit removed from an 2005. All of the diagrams I see say they use different exhaust. Just wondering why, or if it can be modified to fit my 2003?

Thanks

davelinde

I think a catalytic converter showed up mid year 04

Fiftygrit

I think yours is 3.5in and the 05 as is my 06 is a 4.0in, it may adapt, if so you may drop your EGT`s if you can get it for cheap I would try and make it work.

Spooler

The 03' to 04' trucks have a 3.5' down pipe from the turbo. I am not sure where it goes to or if it goes to a 4' exhaust. The 04.5 up trucks have 4' turbo back. Aftermarket exhaust for this is usually from cat back. So, the exhaust can fit but you will need the newer trucks downpipe and some additional 4' exhaust pipe to run to the 05's kit. If you get a kit for an 03 to04 it will be from turbo back for the good kits.

SHARPMACHINE

So, they have the same turbo flange etc...?

His kit is complete, turbo back. No cats on either one.

Thanks for the replies guys.

st.rodder2

The 03 - 04.5 do not have a cat. Stock is a 3.5" downpipe then changes to a 4" about 6" or so from the turbo flange. Aftermarket systems start at the turbo with a 4" all the way back. You will need to adapt the 05 exhaust to your stock pipe.

SHARPMACHINE

So, the rear turbo flange of the 03-04.5 is smaller than that of the 04.5 on?

michael/edge

My 03 came stock with a 4 inch down pipe and exhaust

pmtg

You should have the HE341 on the 03, so the exhaust elbow will have a 3.5" outlet. The elbow from the 05 will have a 4" outlet. If you find a new exhaust elbow (one from a HE351), you can clamp it to your 341 and use the 05 exhaust.

Or, you can eliminate the elbow and get a HX40 style downpipe and get the adapter to mount the HX40 flange directly to the 341/351's flange (where the elbow would mount to the turbo)...http://www.cumminsforum.com/forum/3r...-downpipe.html

Here's a side by side of the elbows, the one on the right necks down to 3.5" (the one you should have on your truck) and the one on the left is 4" for both inlet and outlet (like an 05, or 04.5+)...

Jim O

No it didn't It is just like ptmg said I just changed mine this past week and it was 3-1/2 to the muffler and 4" out of the muffler. I replace mine with a Flo-Pro system that has a 4" pipe that necks down to the 3-1/2" elbow. This allowed me to retain the early Jacobs exhaust brake. (The ex brake replaces the elbow).
Jim O

michael/edge

interesting. Cause a few years ago I was going to put 4" from the turbo back. Well it was all 4" already and the cast elbow looked to be stock. The truck only had one previous owner and I doubt the old man replaced it. so I guess I really don't know how I got 4"

Jim O

I bought mine new and it came with 3-1-2" to the muffler and 4" after the muffler. When the 04 1-2 came out a lot of 03 owners up graded. I might have as well if I did not have already installed the 3-1-2" exhaust brake.
Jim O