Interesting Exhaust Experience (Donaldson M090544)

I recently changed my muffler to the Donaldson M090544 and wanted to post a report. The history is that a few years back I replaced my stock exhaust with a Banks "monster" Cat back exhaust (4"), but found it to have too much drone, so replace the Banks muffler with a 41" Donaldson. That was still a bit drone-y so I put a resonator in front of it (between Cat and muffler). Was good enough for a few years but was never totally happy with the sound when towing (esp in 3rd gear and 2000+ rpms). I bought the 51" Donaldson and put it in place of the resonator and old muffler. WOW what a difference in sound/tone. Love it. But my main reason for posting about it is that I also noticed a drop in EGTs. I am seeing a drop 100 degrees or more. I did not expect that. Maybe the combo of resonator and 41" Donaldson was causing back pressure? Regardless, I am definitely getting an EGT reduction benefit on top of the greatly reduced in-cab sound profile.

 

I have the same drone issue because of a change to a MBRP 4" cat back exhaust. The muffler is only 16" long! No wonder I have drone! I have been looking at posts on exhaust modifications and this seems to be the best solution. Is there any way you could post some photos of the install?

 

Does this work? The 51" Donaldson is really much quieter. I have not yet tested it with towing but just the sound difference driving unloaded leads me to believe this is "the one"!

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Thank you! What a beast! Here are the attributes off the Donaldson website:

Attributes
Inlet Diameter 4.02 inch (102.11 mm)
Outlet Diameter 4.02 inch (102.11 mm)
Body Diameter Maximum 9.01 inch (228.85 mm)
Body Length 44.44 inch (1128.78 mm)
Overall Length 51.00 inch (1295.4 mm)
Rated Flow LR 1158 cfm (32.8 m³/min)
Rated Flow MR 1639 cfm (46.4 m³/min)
Rated Flow HR 2006 cfm (56.8 m³/min)
Back Pressure Low-Range 0.98 inch Hg (25 mm Hg)
Back Pressure Mid-Range 2.01 inch Hg (51 mm Hg)
Back Pressure High-Range 2.99 inch Hg (76 mm Hg)
Attenuation LR 13 dBA
Attenuation HR 18 dBA
Style Style 1

 

I was running the 40” Donaldson and had to add a resonator due to the exhaust brake noise.

With my new exhaust this last spring I installed the same M90544 and am also quite pleased!

No drone, good tone, and no exhaust brake noise.

 

Thanks for the confirmation. I ordered mine from Ryder Fleet Products Monday around noon and I received it this afternoon (Wednesday). Amazing service! The price delivered was $131.56. Seems very reasonable. I have an appointment to have it installed Friday. I'll be on the road Friday evening for a three hour drive so I'm hoping the drone will be gone.

 

Any updates? How do you like the new Donaldson?

 

What a difference! Fired the truck up at the muffler shop and walked around the truck and noticed it was a lot quieter but still sounded good. Jumped on the freeway leaving the muffler shop and noticed right away a substantial noise reduction at highway speed. I actually was able to hear my tire whine which I had never heard with the new Toyo M-55's. I also noticed I was listening to the radio with a lot less volume. Most importantly the drone was gone. I heard no drone during my three hour drive Friday evening and then back again Monday morning under unloaded conditions and just a couple mild grades. The final test was pulling into the parking garage at work Monday morning. I have actually set off car alarms driving through the parking garage! Amazing how much the noise level has been reduced!

One reason my MBRP exhaust was so loud was due to cutting off the pipe just after the muffler and turning the exhaust tip down in front of the rear axle (closer to the cab). I have a flat bed on my truck and added mud flaps which apparently interfered with the tail pipe which eventually became damaged forcing the modification. That's when the noise became unbearable. I decided to have the muffler shop just turn the exhaust tip down just after the Donaldson in front of the rear axle to avoid any interference with the mud flaps so my before and after comparison is a true apples to apples. I would assume that it would be even more quiet if I ran the exhaust out to the rear of the truck. Overall I'm very happy with the Donaldson! Thank you for the recommendation!