Hey, I know there is a few guys here running Donaldson mufflers. Couple questions: What size? I mean length, diameter, etc...
Does Donalson make a muffler that has a 3.5" inlet and 4" outlet?
Donaldsons website kind of tough to navigate, couldn't find these answers. Does everyone have the off-road muffler or what? Local truck shop has them on sale, so I am wanting to get one. I remember a while back a few folks saying the flowed good and sounded good. Thanks-Steve

 

I'm running an off road Donaldson: https://dynamic.donaldson.com/webc/W...210&item=22723
Picture: http://shop.airflowonline.com/Mercha...egory_Code=EIO

Sounds great. Slight drone at exactly 1500 rpms, not present just above or just below. Can get your attention at WOT with the fuel turned up.

Probably not going to find one with a 3.5" inlet and 4" outlet, however, you may be able to get away with a 4" to 3.5" reducer.

 

Thanks AK Ram- I'm kinda jealous, cause a buddy has his 12v straight piped and it sounds like he's got a ISX under the hood, so hopefully I can get my 03 to sound that good. I'll get to Anchorage the first week of Oct, I wish sooner. I'd like to hear your rig. Hopefully I'll get the sound I'm looking fo w/out straight-piping. After all I've heard about 03's sounding like rice-burners when straight piped, I figure the Donaldson should sound better. Did you buy the 4" to 3.5" reducer somewhere or did you have it made at a muffler shop? -Steve

 

I have 4" from the turbo back, so I didn't need one. A 4" to 3.5" is a hard request. Most regular exhaust shops don't use pipe that big, so you may have trouble finding it locally. Might luck out and get one at a big rig exhaust shop. An alternative if you don't mind paying shipping: http://shop.airflowonline.com/Mercha...tegory_Code=EA

 

All else being equal (meaning using stock pipe on truck), is the Donaldson muffler louder than the stock muffler? Is it a straight through design so it has better flow?

 

Straight through design with lots of flow, deep tone, good bit louder than stock when you get on the go pedal. Not much louder at idle. I beleive they make a longer version of the same muffler that is quieter. Some folks were discussing it here about a month or two ago.

 

Nope....louder is good.