if you replace the airbox you definitly need a fuel computer.
I have the cobra fi2000--plugs right in,no cutting,hardest part was taking the tank off to get to the injector wires. (also one of the cheapest and simplest to use)
as far as the hypercharger I was looking into that one but I have forward controles and was told that it sticks out too far and would hit my leg.
there are 2 types--regular w/open front and one with the butterflies that open when you twist the throttle (harder to install)
If you like it you should get it,they have cool accessories for it also,check out cruiser customizing for pics of parts.