I know some of you can't get your truck loud enough and like to scare children and want everyone to look, but I like comfort and quiet. I'd prefer the stock exhaust and I may find one if I can't get mine quieted down but first I'd like to see if I can. The 4" MBRP exhaust was on the truck when I bought it. The thing was straight piped and I added the 30" muffler. Helped immensely but it's still too loud in the cab and there's droning at certain rpm. Not a big deal on short drives but we use the truck for hauling and towing on long trips and that's when it becomes annoying.
It looks like there's enough room for another muffler to easily fit (CC SB). Or I've thought about removing the MBRP muffler completely and putting on one of those crazy long Donaldson mufflers. Think a 2nd muffler would do much at all? Or get one long muffler?

 

My recommendation for a quiet'ish 4" exhaust would be a 4" Magnaflow cat with a 4" Donaldson muffler.
Or 4" cat w/4" resonator and looooong 4" muffler.

Catalytic converters can really cut down the noise.

 

That probably would be quiet, but I don't intend to install a converter.

 

When upgrading exhaust, i played around with and without the cat. The only thing i noticed was a lot more noise without it.

Granted, this was with a stock truck. Did not notice a decrease in egts or any change in turbo spooling whatsoever. A lot more noise, the drone, and lots of turbo whistling noises were more noticeable.

The cat definitely acts like a muffler in that it decreases noise, but I'm sure you don't want to spend the money buying one. If that's the case, I'd find another muffler. Probably best to have 1 only, but if you had to i guess an additional 1 could work if you can find a way to make it fit

 

5" mbrp here but with the cat. I couldn't take the high pitch whistle at high idle without it. I tried both. With cat no muffler it sounds great and is pretty queue in the cab in fact unless your getting on it with the Windows up you can't tell a difference between the 5" and stock.

 

Is your tail pipe sticking out past the bed side or is it tucked way under?

 

That's what I am running, took 90% of the 03 whistle away. A cat was next but I am happy with this.

 

It terminates past the bed side.

 

There is room to add a second muffler. At least a glass pack style/straight. I ran a 5-in and was very unhappy with the drone. Added a second muffler in front of that one. Having more than will will have a resonator affect and help it a lot. Even so, mine is still a bit louder than I would like at times. But everyone says it sounds really good. These are the simple straight glass pack style I have.

 

What do you mean by resonator effect?

I did some searching on that long Donaldson muffler - appear to be fairly popular among the Dodge guys. Think it would work well on a 6.0 too, and i guess they are pretty cheap to get a hold of

 

Are you saying the second muffler helped a lot with sound and drone or is it more of a diminishing return effect?

 

The other option is the walker BTM. Btm stands for big truck muffler and popular with 7.3 guys. I had it on my old 7.3 ex and it sounded good with no drone that I remember.

 

May be poor wording on my part. I was comparing to the factory setup where they put a resonator(small muffler) in the exhaust toward the rear. I put a glasspack in the mid-section of my cars as well. Space is there to fit and takes away much of the drone in the cars. The theory is related to clamping down on sound waves. Each muffler changes the tone from what it received if I am making sense. I took the resonator application and applied a little differently. I get a more free flowing exhaust without the blat and less of the rumble I do not like.

I started with the MBRP but was to much for me with towing or running over 70. So added a Dynomax in front of it. I was going for least restriction so both are straight thru. Tires make more noise than the exhaust at road speed. And no comments about how loud it is from neighbors or schools. Though you will hear the exhaust note when rolling into it.
Disclaimer would be it is quite for a low restriction 5 inch exhaust.

spdmpo- Definitely a diminishing return. Not like the second muffler makes it 2x quieter. More about drone. It addresses much of the audio the straight pipe guys like. or at least dulls it.

That Donaldson line looks interesting for the price. Depending on which one, Some are going to be restrictive like stock I assume. I know feel I way overpaid for MBRP and Dynomax.

 

I had the same dilemma. I installed a donaldsom M100580 with no cat. It is a very big muffler and barely fits but it does fit. It is a 5" straight through with some mesh inside to direct exhaust flow to the outside of the muffler. It is alot quieter than the mbrp muffler that i had previously. There is still alot of turbo whistle but zero drone and zero "bark" when your heavy on the throttle.

 

I have a 4" system with a Donaldson BTM and am very happy with it. I too mostly tow. It has a nice whistle and only drones on a bit on hard acceleration. Again, very happy.