downunder

Depending on the engine you may actually end up losing power with the higher nitro if its compression is too high. Easy fix though if this happens, just start experimenting with adding head shims. A cooler plug can help avoid detonation if the compression is too high but then the timing is wrong to get the extra power you're after. Unless the oil content goes to ridiculous levels then it has no affect on power because the volume of oil per cycle (which displaces the same volume of air) is so minute you'll never see any difference. What zagnut said is quite correct, in theory, but unless you know exactly the difference in fuel flow rates between different fuels then you'd be taking a big chance cutting back on the amount of oil.