the upgrade path for most is pretty much the same.
exhaust (literally EVERYONE starts with exhaust, these bikes sound great so it's obvious)
all the cheap/free stuff. brake lines, flapper/pair/soft rev, little stick on carbon bits, flush mount signals etc etc etc
then you may see a set of wave rotors (blech), some rearsets and clip ons maybe
after that guys tend to look at suspension (ohlins 20mm fork kit, ohlins/penske/whatever shock)
then maybe an airbox, snorkel, that's where most stop.
then there are some people who just do all the things. they're fucking retarded though haha