NOTHING WHISTLES LIKE A 6.0!!!!!!!!!!!!!!!! I don't care what wrapper you have around it. Now to me that truck is perfect, I like the 6.0 and the Slantnose it my favorite body style....
I know from experience, I could get better mileage out of my 6.0..... but then the turbo does not sing... I have an all stock exhaust, cat and muffler and it still whistles loudly..... completely open... it would be difficult to drive...... something would be in the way of the steering wheel..........
Also, they changed the turbo in the later 6.0.... the 03 and 04 is louder than the 06,07..... I was beside a newer 6.0, when I stepped on the go pedal, my turbo whistle drowned out theirs... and I was on their passenger side......