I used to always fly wide open also on cross country. WOT at 8,000' is about 75% power and I am always 8-13 thousand feet. Since I got the M2 with the fuel flow meter I have changed this. I have found that if I pull back to 19" manifold pressure (fixed pitch prop) which gives me 50-60% power depending on what my altitude is that I get much better range and economy. I only decrease my speed from 191 MPH to about 180, but my fuel burn goes from somewhere over 8 GPH down to 6.25. This also many times gives me one less fuel stop which makes for even more fuel and time savings than going up and down one more time.
One thing that I have found on my plane with an MA4-PA carb is that the last inch of throttle gives me a much higher fuel burn even with the mixture pulled back at just LOP. The experts tell me that there is an enrichment valve in the carb that kicks in for the last bit of throttle to cool the engine on climbs and the extra fuel does not atomize all the way. But aside from this there is still a big difference by decreasing power and it is due to the much higher drag at the higher speeds.
