My PCM is on the way and will be back on the road in a couple of days,have been looking at both 4" and 5" exhaust as my next add-on and am wondering about noise levels and if I should go with a 5".I searched threads already and wasn't able to find any comparisons.I do plan on more mods in the future and thought maybe I could be ahead on the exhaust side but I still want to be able to have a normal conversation in the cab without having to yell,so I guess I will want a system with a muffler.

 

Go with a system with a good free flowing muffler and you will be fine with the 5". Let me know if I can help ya.

 

5" is ok but you'll see better MPG and power with a 4" system.

 

i dont see how a 5" would effect power and MPG, its still only using a 4" DP

 

it doesnt flow efficiently. Now if he plans on bombing this thing to the hilt than the 5" would be fine.

but a few performance mods it wont help

 

I have run both in muffled and straight pipe.

The 4" muffled system sounded best to me. Relatively quiet at idle, nice tone during cruise and great sounding at WOT. Straight pipe was way too much drone for me.

The 5" is just different. About the same overall volume, but not the same tone. Deeper sounding exhaust that sounds "muddy" to me. The 5" straight pipe adds some raspiness. Also, droning can be an issue with 5".

Best sounding aluminized exhaust I have heard is DiamondEye. That's why I carry 'em.

My current exhaust is 5" straight pipe to dual 4". I am running twins and it's like having a factory muffler under here. Quiet!

Dave

 

I guess I should include that I tow a 37' 14,000# camper on occasion (4-5x a year),and was thinking about 100 hp injectors in the future.

 

I don't know that 5" has hurt my power or MPG. As I am getting better than 24mpg unloaded on the freeway.

Dave

 

I also like to sound of Dual 4" Systems on the Cummins

 

I have run 4" duals, 4" straight pipe, 5" straight pipe, and 5" to a single 6" miter stack. I'll say my favorite so far is the 5" straight with a 6" tip. I pulled the stack back off for it. I really have no drone or any complaints at all. I just made a 2500 mile round trip with it and my wife and two kids never complained so it must be ok . I could try to get a sound clip for you but it wont sound the same with my twins as a single.