I think you mean Wattage? It depends on your bikes charging system and what you plan on using for lights.
www.electrosport.com
makes a higher output alternator stator(the stationary wire windings) that charges at a lower rpm than what came with the bike.
I'd recommend using two relays to carry the higher current rather than burning out your high/low beam switch.
If you plan on using plastic headlight housings,consider that they may melt/overheat at high wattage levels.
It's a do-able project, just some careful planning and purchasing will be needed.
