Not really, There is another flight modeling problem there that also needs to be addressed. As altitude increases, manifold pressure should decrease (this never happens in AH, regardless of engine). In a supercharged engine you can set this effect back, but still, eventually, manifold pressure will decrease, and when it does, your burn will also decrease.
If you are pushing a set pressure, your burn should remain unchanged. It can not increase... The only thing that could increase it is increasing the MP or enrichening the mixture.
However, I did level at three different altitudes and the burn did not change in level flight. At higher altitudes, more fuel was consumed. Its incorrect.