dont buy the impulse vision, buy the normal impulse (about £100). The vision just stops you from breaking balls. In a month or so WAS will be releasing a board for the impulse which has an eye, turning your impulse into a vision, for about £80-£90. The board also upgrades your ROF, increases efficiency and is all round better.
Another upgrade to consider getting is the HSW i-frame, this is a trigger framethat allows insane rates of fire.
p.s don't get a silver bullt, they are nothing but shiny spyders!