I've been looking around the forums for quite some time trying to determine the best muffler for my truck. The factory exhaust is way too restrictive, so I'm doing some testing without some of the emmissions stuff. I'm on a tight budget, so i've been waiting for some good deals to roll around, and one finally did. I picked up a magnaflow muffler, 36" length for less than 50 bucks brand new off ebay.

Before Thanksgiving, I hauled a 14000 lb load 300 miles to my parents house, no noise at all from the stock muffler. I put my truck up on the lift, and replaced the muffler Thanksgiving day. Loaded up and headed back with the same load.

No load empty truck, sounds great, not loud unless i get on it. Loaded is a different story. The drone is so bad that I can't hear anything, and wound up running 85 to get away from it.

My main question is this, I've heard two things that are absolutely wonderful, Donaldson 51" mufflers, and Aeroturbine 4040xl. I want my truck to be as quiet as stock, or even quieter with better flow. Is there someone out there who has had both and can give me pointers?

 

I have the Donaldson and the truck is great on the interstate pulling a trailer.
No droan.

 

X2!!!! I have the 5" donaldson and i have very little drone but I also have a 7" stack but it exits right behind the cab and it is very liveable... My daughter only conplains with a veryl large load but with twins there is no lag so drone is very minable... Honestly there is less drone with the stack than with the true 5" system!!!

 

Put the CAT back on also.The restrictive part is the muffler.Cat will help on drone some and you are still legal.

 

It's pretty well accepted that the 51" Donaldson is quiet and free flowing. They also make shorter ones if you want a little more noise than stock. I've got a 41" on my Mack and that's what I'll use when the time comes to change it out.

ps....You'd probably like the Magnaflow if you replaced the parts removed for testing.

 

Thanks for all of your help! I'll be headed down to my Cummins dealer to purchase a 51" Donaldson.

P.S. no more kitty = 2 MPG better, plus in NM, we do not have to get tested for emissions

 

Hang on to it as truck can't be resold or traded in legaly without it on.

 

Check around a little first. There can be a big spread on prices. I think I heard of guys getting them for as little as $50 bucks, but you have got to shop it.

 

Hey bud,Been down that muffler road,had the same magna-flow the drone was horrible took it off and now have the big 52 Donaldson on it and its a swb quad cab very happy with it empty and pulling my toy hauler.

 

I know nobody will believe me but.....my truck had way less drone(almost stock) after I straight piped it(no muff). This was coming from the mbrp 4". It is louder outside but quieter inside. Last week, I was towing a 25' gooseneck with lifted jeep and 2 4wheelers at 75mph and it was way quieter than I was expecting.

 

I went to a big Truck Dept. for parts and asked for a Mack straight thru Muffler 4" in and 4" out sounds good no drone and I pull about 15000 lbs on a reg. basis. no drone either. forgot how long it is though I know it is not 50inches long. about $60.00 what it cost.

 

The 51’ Donaldson is louder than stock, but the engine is still louder then the exhaust. I punched out the cone baffle in my Donaldson.


I had a strait pipe, but that got old on the highway. Well, it wasn’t bad with the GV OD, but too loud towing or cruising in the woods. Sounded good in town however, but given all conditions the Donaldson is the best.

I’ve always had a kitty cat too.

 

Well I believe you because I got rid of my muffler(kept my cat) and I don't get any drone. Sounds fairly quiet in the cab and awesome to bystanders outside.

 

I am also straight piped and dont mind the sound sure there is some slight drone when pulling up a hill heavy but nothing bad what so ever it is A LOT quieter and basically no drone compared to my old 96 straight piped cummins.

Different strokes for different folks I guess

Oh and you stole my Avatar

 

Well that's as clear as mud. Some say 51" Donaldson other say ditch the muffler....