The point was - they are inversely proportional.
The only way to increase HP is to burn MORE fuel (and air). cooler intake, larger exhaust, etc...
The only way to get better mileage is to burn LESS fuel. Plenty of ways to do this, smaller motor, more air pressure in tires, aerodynamics, etc.....
This is physics, just get to pick one
Then again - this may help:
http://www.ebay.com/itm/For-BMW-Inta...4b2862&vxp=mtr
