Probably not alot. The only bike I know for sure that matched up were the 600s. And that would be a downgrade.
The best thing you can do is a 520 conversion with a -1/+2. DiD xring chain and renthol sprockets.
Also for suspension.. just get your fork oil changed to a nice Ohlins synthetic fork oil. New bushings and seals.. the difference is OMG!
Of coarse, the standard stuff... pipe, jet kit, undertail, CLR tail light, frame sliders.
On the brakes.... is your year running the 6 pot frotn calipers? The 4 pots are suppose to work better and they were on my 2002. I think I can get you a up close pic of the caliper if you want/need to compare. You can do some stainless steel braided lines, synth brake fluid DOT 4 and some HH sintered pads. That would equal some HUGE braking upgrade!!!!!
aka Gas Man
Was: 2002 Kaw ZX-9R
is me till the