I just found another test that listed 525's at 60.15 gph Per side @ 5000 rpm's
Tested in a baja 40
(just google fuel consumption for mercury 525s @wot)
For the ilmor, that's 43.7% of the 525 consumption @5000 rpm's .
I know it's apples vs oranges comparing a 41' fountain p1 boat vs baja 40 pleasure, but you get the idea at least.