Batbiker, yeah increased performance usually means decreased fuel econ. but certain parts may increase, like intake and exhaust with a spot on tune should give you same mileage. tho the extra power makes you twist the throttle more often, but also when I did a built motor in my old dyna, I was getting almost the same mileage on highway, city was piss poor because the cam choice made no torque in the lower rpms. So depends on how your setup is.
2012 Road Glide Custom Vivid Black named "Becky" with a simple motto "If it came from the factory like that, it doesn't belong on the bike!"