Fireflipper
Hi Dudsty
You do not say what you are pulling. I would call Ford customer service and ask if a exhaust brake would void any or all of the warranty. I have a Chevy 3500 diesel with the Allison tranny, it does a good of keeping the speed down while going down a moderate grade, but as I discovered recently going through Donner pass it still picked up alot of speed, but that is a pretty steep grade.
I also have the air bags, don't really need them with the dually, but I had them on my 2500 SRW chevy and the dealer would not allow anything on them when I traded it in, so off they came and they fit my new truck. they do make the ride a little smoother when the truck is not towing.