What is the part number for the 4 inch muffler with out the baffle? Is one better than the other? I have tried so many setups and i think that what i've found is that these are going to be my best solution. Is there any way to get the throaty rumble yet with no drone inside the cab when pulling a trailor?

 

Nelson/Fleetguard is 86131M. It's not really throaty/rumbly, but its a straight through design, and if you install only that you're not likely going to see any losses.
I'm pretty happy with mine...I'll be even happier when my AFE stage 2 SI comes in and then it will be quieter at both ends of the truck!

 

Got the 52inch donaldson 4inch straight through. Love it, towing on the highway I can barly hear it. Under throttle its got a lite but really good sound. Around 1200 or so it sounds like a monster, but the biggest thing is no drone. I cant stand drone towing on the highway.

 

The part number for my 40" Nelson is 86127, 4" straight through.

You might find these helpful:
Nelson catalog:
http://www.cumminsfiltration.com/pdf...s/LT32002C.pdf


Cross reference:
http://www.cumminsfiltration.com/pdf...s/LT32002F.pdf

 

what is the quietest muffler that doesnt restrict flow?

 

I had a flowmaster,magnaflow and now a 5x 51 in nelson with reducers to 4 inch.I tow heavy,no drone,really like the sound,it is quieter at idle than my neighbors 07 5.9 stock system,he was even impressed.

 

How was the magnaflow before you went to the nelson? About to try one on my second gen.

 

That's the million dollar question!

I've never heard a 51" but my 40 is not noisy at idle with no drone while towing, louder than stock when you get into it by not obnoxious like some after market mufflers.
Pics of mine in my gallery.

 

Fisherguy does your 40 " have a hissing or pfffff sound like the one on youtube? do you have a sound bite?

 

I don't think so, no I haven't shot any video of it.

<edit>
I do get some turbo whistle back there I think.

 

i had the magna flow xl system and it sucks loud and big drone so I cut the muffler out and put in the donaldson mo85171 no baffle 4 inch in 4 inch out .no drone what so ever , at least 50 -60 % quieter perfect muffler low rumble . but very small whistle out back this seems to be the norm.very happy. purchased from rider fleet products for 68.25 plus 2- 4 inch stainless ban clamps part # 89527b and shipping for a total 90.90 kurt

 

67 Hotrod, the magnaflow has a sharp sound to it, also some drone pulling ,it was the quietest one they make,really good flow,like the nelson .

 

has any one tried the Walker 12147 straight thru?