Since I put a 5" DPF delete on I had to take off my tailpipe section. I was doing it today and noticed something about the muffler, um.......it doesn't muff. It's just a can welded around a solid piece of 3.5" pipe. So it's kinda making me wonder how the exhaust people are getting 20hp gains from removing the "muffler". Even if you're putting the larger diameter pipe on it's still necked down to 3.5" after the DPF. Anyone got some dyno numbers from before and after? Here's some pics:

 

I would not belive those who claim 20hp gain, it is rather impossible, 2-6 hp gain is more likley. Besides if you put too large diameter pipe you can even lose some hp.

 

I was thinking that it's probably more of a vibration dampner. Ford is famous for those on a lot of their vehicles. I put a MBRP with no muffler on mine last week and all I noticed is that it looks better but the tailpipe shakes more when the truck starts up.
At least you get to get rid of that 50# anchor...LOL

 

boy, that's something else....I wonder what FMC charges for a "muffler" like that?

 

It may also be a "resonator"

 

Or part of the system to control or protect other components from pipe temperatures aft of the DPF.

 

Ding, ding, ding, we have a winner. There is no muffler on the 08 Super duty trucks. Ford has never said there was one. Look at page twenty of this file and look at the list of parts. http://www.backglass.org/duncan/ps64...4_overview.pdf

 

Sounds as though your getting it al fixed up fine. Wondering if you had considered the egr removal/ or if its possible?