I wish I could have dyno'd before and after adding it. My truck still feels very strong and I am much happier with the sound now then before adding it. It still sounds very good outside of the truck. When I 1st pulled out of the garage my wife was outside saying it was still loud. Not when she went for a drive. I know I had stated it felt like it lost power. I have no way to prove or disprove that. If the noise is bothering you then you will not be sorry.

 

You're the only person I've ever heard complain about the 51" Donaldson or Nelson. Also 1300-1400 RPM seems awful low to be having 'drone' problems. Are you sure it's not rubbing on something? Is it only hung from rubber isolated hangers? Something's not right, even my 40" is quiet without any drone.
Is your cat in? I've heard removing that makes for a noisy ride...

 

Fisherguy.. I don't think he was complaining about the muffler.. I do not think he has decided to try it yet as he is afraid he will lose power..

I do agree with your comment on drone.. I know in my truck before adding the Donaldson it was 2k that was BAD.. Below 2k was great and I would have been happy if that tone was the entire rpm range.

 

mine still has a mild (very mild) drone under moderate and full throttle with a load with the 51" donaldson x 5" in/out straight through muffler. the idle tone is good and the exterior noise has throat but does not reverberate off of everything.

i posted a second ago i didnt notice any hp change to speak of on the dyno

 

I have been very happy with the one in my signature line.

 

Till your post I had not heard of that one. The flow & sound numbers posted here tell me it must be pretty darn quiet while still flowing very well. Are you using 5" anywhere else in your system or just reducers for the muffler?
Did your kitty test pipe take care of changing the angle for a straight system, if so what brand is it?

 

I installed a donaldson m120100 a while back. It has the same flow as the 4" version of the 51" donaldson that many are using, but is a direct replacement of the stock muffler (just need to weld on hangers). I think that if someone were to install it on your truck without you knowing, you probably wouldn't notice the difference in sound over the stock muffler. It seems to be just a little deeper outside the truck, while allowing a little more turbo whistle through. Off boost response has improved a bit. This looks like a good muffler for the guys that want better flow and performance, without the additional noise.

Mike

 

OldSmoky, did you go 5" the whole way, or did you use 4" to 5" converters?

 

I have the Aero with the stacks and it is loud in side the cab. Has any one herd how the Hush Power muff is?? I seen there both in Kentucky that guy said he had the best one on the market. NO drone in the cab??
what do you think??

 

It is 4". The muffler is offset like the factory unit, and the same length. So, all you have to do is to cut the old muffler out, and slide the new one in. I cut the hangers off of the factory muffler, and welded them onto the donaldson. Besides that, the exhaust is completely stock.

Mike

 

I see you also have an 03 model which was original 3 1/2" from turbo to inlet of muffler and then 4" out of the muffler. If you have aftermarket 4" exhaust pipes I.E. from the turbo to your muffler you might want to consider an 04.5 - 06 stock muffler 4" in an out. That is what I finally settled on to maintain my sanity. Let's face it the turbo is the biggest restriction in the exhaust system. Nice thing is it will fit the factory muffler hangers and I'll bet you could ask a muffer shop to give you a call when they get a post 04 model in and purchase the later model stock one pretty cheap. All you would need then is a 4"+ tailpipe expander to take the clamp crush out of the pipes from the factory muffler clamp. Just make sure they cut the old muffler out of the later model truck on the pipe entering and exiting the muffler and not the muffler inlet or outlet.

L8r,..........dogger

 

Anyone looking for a Donaldson or Nelson type muffler should check for a local Fleetpride Dealer.

Here are Flow rates from Donaldson on some of the mufflers discussed here. Also a cross reference chart from a Fleetpride catalog.

 

On the other hand maybe the oem muffler ain't so bad for low noise & decent flow.
The M085421 is a 40" oval muffler spec'd for the 5.9 Cummins, 6.6 Dura and 7.3 Nav with better flow numbers than the popular 51" M090544.

I wonder if that M085421 is the oem muffler or is built the same as oem?

 

Here's a 5"in/5"out on ebay for $53.

http://cgi.ebay.com/ebaymotors/M1004...temZ4614188401

Anyone think that would work well?

 

M050944 is the 4" in 4 " out part number for the 51" with perforated baffle on the Donaldson muffler if I recall. I am extremely pleased with mine, no drone, no cat, and the 6" tip makes a little deeper note OUTSIDE of the cab.

Wood