It is really, really hard to choose an exhaust system based on what others tell you. For example, some guys base their opinions on performance first. Sound and looks are more important to others. When you hear and see something you like just ask the rider about their setup. As far as your fuel injection goes, switching to slip-ons is still going to change your air/fuel mixture so a new map may very well be in order. For more info check out this tech article, Jetting and Fuel Injection Adjustment, Pipes.