21 mpg highway, 17 city - 1 mpg better than without the supercharger, more likely due to better fuel management. Passed a slow driver at 50 mph in 6th gear, was at 80 when I tucked back in. Performance is smooth as silk; if you didn't know there was an engine mod, you'd never guess it. The piggyback management system only kicks in when the blower is making boost; otherwise, the stock ECU handles the fueling.
Will see what the mileage is like with the Pulstar plugs.