Mileage of your baggers?

When it comes to gas mileage, I feel my stock 07 FLHTCUI is a piece of junk compared to a few of my friends bike and a couple of my previous bikes. The 07 varies anywhere from 29-35 mpg (23mpg the worst)around town and 36-38 mpg on the open road. In comparison to my friends when we refuel, I am taking a half gallon and more at each fill up. I have ridden to Yosemite and back, fully loaded and two up and had gotten 43 mpg and 38mpg, but when I tested my mileage by myself (continious freeway at 75-80mph) I can't get better than 38mpg. Recently I added the high flow air filter, download, tried again (the same route)and got only 32mpg. Couple of weeks ago we went on a ride up highway one, two up rarely in a higher gear and got 43mpg. What fustrates me is, my friends 07 streetglide, from Truckee to the bay area, over a 200 mile trip, two up and fully loaded, one tank averaged 47mpg. Also the dealership/H-D Customer Service doesn't care enough to diagnose it saying its normal and it would be better as it breaks in. I've got over 6K miles on it, how broke in does it need to be?  

I have an 06 FLHTCUI (30k miles on 'er)and gets up to 47 mpg fully loaded with the wife on back. then by myself just cruising to work I get 35 mpg.  the difference is that with the wife, I ride no more than 65 mph. by my self I ride upwards of 75 plus. the wind resistance at these upper speeds really rob's the bike of mileage.
I also have a BMC with a 100 inch Revtech and a 6-speed. I get the same results with the two differnt riding styles. mellow riding equals good mileage.
there is a cost associated with having fun...

good luck

unclepsycho