To make a streetfighter, you usually rip off all the fairings, and the clip ons, put on a set of bars, and a different headlight. If you want to get all into it, chop the subframe and make it a single seat thing (those are really big in europe, I dont know why). You can finish it all off by jacking the rear up abit (affects handling, makes the bike more twitchy) and then getting every silly metal cover you can get your hands on.
A headlight conversion is about $200-$300. Consider another $400 for handlebar conversion. $150 or so to jack up the rear. Don't know about redoing the subframe, but that looks expensive. And, you completely ruin the resale value of your bike, at least you would here in the states.
You could just look into something like a z1000/z750 or a ducati monster