4" or 5" donaldson on stock exhaust?
 

I am wanting a 51" donaldson , but am not sure on the 4 or 5. I am looking for the best flow and am not sure if leaving the baffle intact or altering the baffle is better. Just trying to kill the drone and keep a little sound. TIA

Wood

did the 4" on mine, punched out the baffel with the cap for a hp cylinder (not as easy as i thought it would be) alot louder that i thought it would be, but no drone so i guess its ok. dont think the neighbors like me too much @ 5 in the morning

Get the Donaldson M090535 muffler. It's a 5 inch inlet/outlet straight through muffler and has no cone baffle. It's one of the best flowing mufflers they make. I have one on my '98 12 valve. Very happy with it. Here's the link to Donaldson's muffler catalog:
https://dynamic.donaldson.com/webc/W...?section=10194 Here's a link for a picture I posted looking through the muffler showing the straight through design:
https://www.dieseltruckresource.com/...2&ppuser=38118

That's what my dad did to his 06 and it sounds stock in the cab with the windows up and has a nice tone outside the truck. That is the set up I am going to when I do my turbos.

Thanks for the replies. I am not wanting to get into 4-5" adapters though, those things are like 30bucks. I need to be able to hear my customers when they call on the cell phone (which I wear the earpiece for), so is baffle intact or baffle delete a major difference? If somebody has tried either setup?

Wood

I have the 4" with the baffle removed. My wife didn't even notice the change inside the cab. You can tell a differnce with the windows down. :cool:

I like my 40" Nelson, 4" straight through with no baffles.
Part number 86127, got it at my local Cummins store for $67. Nice deep note to it, not obnoxiously loud like many of the "high performance" mufflers lotsa people have.

You'll need some kinda bend or offset if you're replacing the stock offset muffler if you want your tail pipe to be straight, you can get them at the Cummins shop too.

Pics in my gallery...

Thanks fish, what about drone withthe Nelson if any?

Wood

No drone, not really much louder than stock.