Duck
Sarcastic remark goes here
Usually when you increase horsepower, Fuel economy goes down.. Just like when I lean into the peddle, The further it goes the more fuel is burned.. I am happy with the fuel economy out of the C-15 in the 07 KW and the Western Star..
If it increases power just by spraying more fuel at the engine, it's unlikely to increase MPG. If something increases HP by making the engine burn the fuel more efficiently, then yes it is likely to increase MPG.