I have a 96 2wd with the Banks full powerpak, AFE filter. Even before the banks, I rarely saw 16MPG. I average nor around 15-16. With a loaded rig (8800 lb trailer) I see 11-13. I'm not complaining, and those 4:10's dont help, but I'd love to see 18-22 too. But just remember that it could be worse- you could have a v-10 and be getting 7-10!
Kev
Kev