I have found in my many years of motoring, if you want to go fast, buy the fast machine. By all means get a little extra out of what you have if its an easy mod. But dont believe the hype. The big bore kit, the performance filter and jet are all hype. Just enjoy what you have, the freedom to go where you want when you want with a reliable machine. I have 2 fzr 1000 exups (145 bhp), i enjoy them to the max but i have no problem nipping into town with either the agility 50 or the peugeot trekker, there all just as much fun as each other in their own way.
Its all about the experience of biking not the bike your on.