On a stock 2006 5.9 cummins, what is the size of the turbo outlet? How about the rest of the stock exhaust?

Tomorrow I undergo surgury...gettin' the cat cut out! . Should be interesting to see the difference. It's a cheap upgrade.

I wonder how much improvement there would be to go from a stock but cat-less system to a 4" cat-back aftermarket exhaust.

 

It is 4" from the turbo out

 

is it also a 4inch on an early 04?

 

Yes it is but the early 04 has no cat.

 

I believe the 305 engines have 3 1/2" exhaust systems. 325 engines have 4" turbo back.

 

early 04 is 3.5" from turbo to muffler (no cat) and then a 4" tailpipe, muffler back. 04.5 and up is 4" from the turbo back w/ cat and muffler

 

If your only loosing the cat you may not notice much. I hear the cat is a pretty good flowing piece. The muffler is more restrictive IMO. That's why mine is gone

 

Mine had the 4" from the turbo stock and no cat, maybe it was close to the 04.5 date so they used that, i don't know......

 

I'll post tomorrow to let you know how much of a difference. I like doing one thing at a time...the truck is an experiment! I've heard opposite, that the cat is the restrictor in the system. We'll see tomorrow and I'll let everyone know.

After the cat is gone, I've ordered some gauges and will install them. I can then monitor for some of the improvements. I'm excited because the gauges I purchased are PDC (Pretty **** Cool!). I'll take pics at that point and post them...I don't think anyone has done what I am about to do with the gauges. (I went a little crazy)

Also, I think I am going to purchase an ATS manifold tomorrow and install it after I get the gauges, since one of manifold has a tap for an EGT...

 

Awesome! I'll be keeping an eye on this for the results!!

 

No. 3.5" to the muffler, 4" muffler back.

Nope

Everything I have read says the same. Thou I am missing my Cat and OE Muffler.. Thou I didn't notice a huge difference.

If you had a 4" turbo back its either a 04.5 with a 325 and had a cat, or its aftermarket on a early 04. Dodge does/did not make a 4" no cat system.

 

I asked this on another thread but this one seems to be more geared toward pipe size. I have 3.5" no cat, would I benefit enough replacing the entire system with 4" to offset the cost difference over just replacing the stock muffler with a good aftermarket?? I'm not after noise, more concerned with payback in performance/efficiency. Thanks.

 

You may try to find a 04.5+ 4" exhaust and have a cat delete pipe and different muffler put in.

 

Hey dude! I'm in Edmonton too.
Looking to do the same as you. Heard that also Cat is restrictive - no its not it is the muffler - blah blah... Don't know what to believe!!!
I want quiet performance.. I'm thinking no Cat & 42" Donaldson.
I have a Bully Dog, CAI & Banks High Ram right now.
Also looking at a NADP Tranny.
Am interested in what happens with your unit.

 

Good idea!!! Find someone that's replaced their stock system with an aftermarket and buy their throw aways!!

I like your Avatar. Are you still flying?? I'm Army, Vietnam, Desert Storm, two tours to Iraq.