Umm, Switched to Silkolene Pro-4 10W40... That was a nice change.
Trimmed rear mudflap, that was free...
Trimmed stock seat foam, that was free...
Switched to Metzler Sportec M1's, Honestly this is prolly the biggest improvement, made a huge difference. Forget about adding more power with a pipe or any of that crap. You'll be spending a grand or so on power you will never use or miss. Your not using all the available power the Busa has now very often so why go to all the expense and hassle? Once you've mastered the Busa enough that you are honestly wringing it's neck at every oportunity? Then add more power...
Adding more power before then is silly, unless your just after a particular look or sound.