i see someone said a free flow muffler might help mpg, ok here is the question i would prob get a 51or 52" muffler which ever one it was, to keep it quiet like stock, will that be enough i really dont want a delete pipe because i dont want a loud exhaust even though that might help too.
do you think a donaldson well be enough for difference

 

Not sure it will help your mileage. Without cat, truck will be noisier with donaldson but not too bad. I have the 5" exhasut with a turn down tip and it's louder than stock but no drone. With cat I suspect not much more noise at all.

 

With your cab/bed configuration, I think you can squeeze the Donaldson in there with the cat in place. Should sound really good, and not loud at all.

I eliminated my muffler (cat still in place) and it did nothing for mileage, but it is annoyingly loud.

 

i have the 51" with the cat (gutted) it will fit.

 

no real difference mpg wise w/me

 

you mean to tell me you can get 51" muffler with a cat?

 

I was thinking of a 40" nelson and leaving the cat what you think ?, better performancs and no louder than stock ?

 

No louder than stock until you step on it, or are towing up a hill, etc. Then it is way louder, and annoying at times IMO. That is my setup now, and I wish I had the 51" Nelson like I had on the 03. Guys have installed it (51" with the cat).

 

M090544, 51" Donaldson part number. fits the stock exhaust diameter. I had mine installed all the way to the rear of the truck, basically meets the first bend over the rear axle. I punched the baffle open inside the muffler to give more free flow to the muffler. Have absolutely no drone with my setup and the kitty is in the shed. The only thing that would make it even quieter in my opinion is putting on a turn down tip. I am extremely pleased with the results.

Wood

 

Mine has the 51" 5 inch Donaldson, no kitty. I put on the turn down tip too and it reduced the noise in the cab. No more cranking up the radio as opposed to the magnaflow muffler.