I recently realized I have driven almost 60,000 miles since having Brazel's Ultra Power installed by DriVer at a Florida Winnebago rally in March 2006. I find it somewhat amazing that everytime I drive this almost 28,000 lbs of MH and toad I am still learning about the UP capabilities.
In the last year I have found that in normal interstate driving a "sweet spot" seems to be around 2,500 rpm which provides 65 mph. It's the old "butt dyno" test - it sure seems to like to run at that rpm.
We have traveled the PA Turnpike and I-70 in PA many times. Recently I found the rig going up some of the mountain grades over the Appalachians at 60 mph in 4th gear at about 3,400 rpm. I cannot claim a marked increase in fuel mileage due to UP, but neither do I see a decrease in mpg in spite of driveing 4 - 5 mph faster than what I used to.
This particular Workhorse chassis sure is a pleasure to drive.
Just my opinion - your results may vary.
FJF
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'05 Itasca Suncruiser 38R, '04 Saturn VUE
BlueOx Towing Pkg, WH W24, UltraPower Upgrade
49 States & 7 Provinces visited in MH| WIT W112365