Mike,
Here's another baseline for you. I'm considering installing a boost controller as well, and I've had a boost gauge on my car for the last 10 months.

absolute max boost at 70-75 mph under full throttle, 9.5 psi
boost at 65 mph cruise, 8.5 psi

22-23 mpg @ 60-75 mph
269,200 miles

Hope this helps-

__________________
Nate Stanley
(Currently Benzless)
1985 F-250 6.9l 170K
2009 SCION XB 36.5K
2003 LS430 78K
2012 Kubota B 2320