The Duramax is actually a Isuzu motor. The ford 7.3 is actually a International motor and is considered the best of all of the ford options but finding one might be a little hard now.
Here are the results! This is with a silencer in my exhaust, my wife hates how loud it is now, and I'll be 30 next month ;) They told me I would probably gain another 15 hp if I take the silencer...