I've been looking into some of the exhaust options that are out there. Most are 4in. systems that I have been interested in. But I was at my local Dodge Dealer today and one of of there techs said that my 2004 HO (not a 600) already has 4in. system on it. Is this true? If so why is everybody buying after market instead of just buying a more flowing muffler? Again if this is so what is a good after market muffler to get. I had a flowmaster series 40 on my 5.3 GMC and liked the tone and the bark it produced, so I dont want it quiet but I dont want it to be unbearable either. Give me some suggestions on what yall think.

 

Some later 04s before the 04.5s came out got lucky and had the full 4" exhaust. I even think they had a larger cast iron elbow, so it's a true 4" system. Somebody correct me if I'm wrong.

If that is the case, I would just get a muffler. People have been happy with the Donaldson and Nelson mufflers. Going from a typeII to a typeI muffler might make the installation challenging though.

 

Put a Donaldson on. I have the MO85171 on and it flows like a champ. Sounds like a big rig, and my mileage has gone up 1 mpg so far. I have only had it on since saturday, but so far I love it. -Steve

 

If in doubt crawl under the truck and take a look. It's pretty easy to tell if you have a full 4" or if you only have 4" from the tailpipe back.

 

CTD in MT, That saying is killing me....

 

will an exhaust system void your warranty

 

The install is easy...just replace the mid pipe with a straight 4" instead of the OEM bend...then the pipe is all inline and the install is a snap.

 

Mind if I ask where is a good place to find the Donaldson Muffler? Thinking about swapping my OEM one with an aftermarket muffler after I get an AFE intake.

Caj

 

Most 2004's had 3 1/2 from the turbo to the muffler.

I installed RIPs 5" straiight system... you can custom order whatever you like for cheap.

It comes with a downpipe that goes from a 3 -3/4 opening to 4". It takes advantage of the larger opening at the mouth of the elbow.