I get 9.0 -- 10.0 gph at 4200 rpm and about 25 mph (depending on trim) out of twin F-115s on my 2510 WA. She has a 14 degree deadrise. On a bluebird day when the water is like a mirror, I've run at 13.5 gph, at 4800 rpm and get 33 mph. Those numbers come from an average of runs with the fuel about 3/4 full, two fishermen, ice in the fishbox, and fishing gear.
At my normal cruise of 4200 rpm, I have about 12.5 hours of range, which should get me about 325 miles down range.
Dave