That's correct! Most all bikes now come extremely "leaned out" from the manufacturer to pass EPA emissions tests. A proper PC setup will help enrichen the fuel mixture... and typically clean up surging and/or hesitation due to factory fuel map config, even with a stock airbox and exhaust. If stock, MPG shouldn't be impacted much at all. Airbox & exhaust mods will impact MPG... more air thru motor means leaner mixture, thus O2 sensors detect and tell computer to put more fuel into motor to keep A/F ratio correct. Good tuners will setup a PC for a "street bike" with a slightly "rich" map to protect the motor. Race setups will be tuned leaner to maximize HP but risk higher cyclinder temps, burnt pistons, etc... I had a Honda VFR800 with stock setup that suffered freeway speed hesitation and bucking... very annoying! A PCIII cleaned it up very nicely and convinced me they are pretty manditory anymore...