If the bike is lean at low/mid range it will most likely me more lean in these ranges if you add a more freely flowing exhaust. Booster plugs are junk IMHO as they simply are a resistor that fools the ECU into dumping more fuel into the cylinder. Typically these are overly rich but they are cheap and they do get rid of the lean condition. A Power Commander with canned maps is not to my liking either. If you want the most out of a PC you need to either spend the money and get a custom map or if they make a PC5 add an 02 optimizer to it so that you can run a closed loop system that will sample the exhaust gasses and make fueling corrections accordingly.