I used to shift at about 5800. Then I backed it down to 5500. Now I shift closer to 5200. No use wasting the midrange torque that 8.3 liters builds. Having said that, I bet a 7000 RPM Viper engine would sound amazing!
I usually shift at 6,000 1st to 2nd and 2nd to 3rd, then about 5,600 into 4th. I spent a day making passes at Famoso some years ago because one of the members on here said if I shifted at 5,500 in stead of 6,000 I would go quicker. Well I tried that and I lost some time. I broke down the time slips into increments (60' to 330', 330' to 1/8th, 1/8th to 1,000' and 1,000' to 1/4 mile) and the only increment that was quicker by short-shifting was from the 1/8th to the 1,000' , which was my 3-4 shift. Since then I've been pretty happy with my results. I realize every truck is different, and I make peak horsepower at 5,600, so I feel the best performance is going a few hundred rpm past peak, therefore I shift at 6,000 1-2 & 2-3, and I go through the lights at almost 6,100.