Lots of exhaust on here but not much about diesels, went with a 3.5" to straight thru muffler then 5" out the side at stock location, sounds great and although to early to say for certain on 1st tank mileage went up by almost 3 gals, calculated by hand, seems the overhead is always off by about 1 mpg.





FM

 

Nice setup! Had similar on my 99 F250 Powerstroke