I like the 5" pipes on my truck. Sounds real nice. My EGT temps are lower which is better for the turbo and oil. Mileage went up 2mpg with the addition of pipes and the tuner. Will average 20mpg @ 70mph no problem.
And..... it runs 8.90's in the 660' with a 1.86sec 60' at a curb weight of 8200lbs!

BTW, Hurst, I wonder if you were remembering my truck when I bought the BBK rear lower arms from you a while back at McD's in NPR or wherever we met up. (those worked out real nice btw thanks)