I've just fitted a £239 road-legal stainless oval Scorpion can. Doing it myself proved to be relatively painless experience, which involved the simple extraction of the standard exhaust, replacement of the centrestand bracket (with a new one that comes with the Scorpion can) and the equally simple bolting on of the new can.
I have to say that I really enjoy the sound of the Scorpion's throaty growl.
Until I can get the Bandit up on the dyno I can't be sure of the power difference (although Scorpion claim an increase of around 1bhp with the baffle in place, 3-4bhp with it removed).
However, the important thing is that the groaning strain of the OE can is now replaced by a deep guttural noise that lets other road users know I'm about.