go up two teeth on the rear sprocket for a 14/39 final drive ratio. very good results here. very short money because you should still be able to run your stock chain. it'll just take adjusting the rear wheel all the way forward in the swingarm adjustment range.

later... the only real mod i can think of is SPS cams and either a full silmotor (or termignoni) system or a custom system based off an ST4 header (45mm instead of 40).
but thats BIG coin....