Can an additional band be added to this gun or can the band be upgraded for better range and power?
It could be upgraded with by adding a band (maybe) or replacing the bands with stronger ones, but I think that would be a waste of time. It is a short, light, maneuverable gun that is not intended to have long range or much power. Most likely it would be overpowered if you changed or added to the bands and would shoot poorly. It would be better to get a bigger, less lightweight gun. A longer Cressi Comanche would be a good choice. But this little gun is very good for its intended purpose.