Outrage

I have 2006 5.9l CTD. The exhaust system on my truck is all stock to the best of my knowledge. Does anyone know what the portion of my exhaust is, what function or purpose it does downstream of my muffler? I am thinking about changing out the exhaust, but not sure what to go with. I am not looking for something extremely loud or annoying while driving long distances. Just looking to improve for better sound and if possible improve engine performance. Any ideas would be appreciated. Also, I am pretty sure my exhaust is 4" from the the turbo all the way down including the cat, muffler, and whatever the next piece is. Thanks

tantruck

It's 4 inches all the way back. If you don't want to get too loud just get a "cat back" system. It leaves the cat and removes the restrictive muffler and has a reasonable sound. It's the opinion of most that the muffler is the choke point. My 2007 has a stainless MBRP cat back and it's quiet enough. Just my 2 cents.

jeephauler

Im please with my 5" Diamond Eye turbo back. I bought the system straight piped and peiced in a Donaldson muffler at first, then added a resonator after about a week to get rid of the drone. Its not too loud but not to quiet either currently. Most importantly it does not drive you nuts towing heavy.

jcismo1

I would go with a Flo-Pro, whether turbo back, or cat back. Just my 2c worth of advice.

gasjr4wd

I bought a MBRP system - the cheapest they had and hated it. Way too loud and a drone that would loosen your teeth driving with the truck empty. Towing was brain damaging. I ended up with a 4" Donaldson M101167 & 30" FTE Res/Muffler. My first idea was to leave the MBRP because it also had the two hangers mounted on it and put the Donaldson in front and the FTE in front of that. They would have all fit, but ended up just using the donaldson and fte. (yep, with my truck I could have ran 3) Some guys use one or the other and it's fine with them. Check the spects on each muffler and what they flow. Not all 30" from the same brand are the same. When people say go with a 40" Donaldson or something and don't tell you what model, it's useless. I think they make 4 of that size that are all different inside. Even MBRP makes something like 8 mufflers, some quieter than others, all the same physical size. The other Donaldson I may have gone with was the M085171.
The reason why I went with Donaldson was they actually post the dBA (loudness) and rated flow. If you want links, let me know. I actually made a list of 8 or 10 possible options before I picked one. I hate doing crap more than once. The Donaldson site also will tell you how to figure how much your engine flows. IIRC mine was at about 1000cfm.
Nelson exhaust is owned by Cummins. That's another option. I think they are made the exact same. Most sites cross reference them.