my set up is like this ...http://www.superford.org/getfile.php?id=80240&toggle=fullsize&filename=NP208F2.jpg
except i have true duels, no cats, duel mufflers, and H-pipe.
i used flowtech shorty headers (with ball hook-ups... the flange hook-ups always leak), 2-1/2 pipe routed stock untill you hit the first gas tank (removed on my truck) i have two mufflers (no flows, glass, ets.) turned up (tall, not wide). my pipes then widen to 2-3/4 and turn away from each other where the spare tires would sit (also removed). pipes dump right behind rear wheels on each side of truck.
i would be afraid to run freaks set up. i can see them crushing, or tearing them off within a month (of course my truck is not as high as his

question - why do so you remove the Xfer case shield ???