The reason the Mustang MAF is being used is its abundance, and low cost. The M44 one is pricey depending on if you can get it, AND it may give a digital output rather than analog, which would just be more work for me. If someone can get me one I might be willing to run some tests, but for now the Mustang one is the way to go. Also, the MAF's output is logarithmic, and is more accurate at lower flows. The M42 will stay in the Mustang MAF's 'lower' output portion, giving it a slight increase in accuracy.