The gen 2 busa still holds its own!!! There are light Pro riders that have been 8.8's on a SWB full bolton gen 2 busa... where the fastest swb full bolton zx14r with Jeremy Tealsey riding has gone 8.70's..
Not too bad for a gen 2 busa with 4yr tech, 1340cc,unported head with stock or small cams vs a 1441,hand ported head and cams... So far the fastest full bolton stretched,air shifter,yada,yada,yada.... zx14r is Lee P's which has been 8.4's and JT's ridden a gen 2 to 8.4's as well...
I wont lie the zx14r is a killer deal for everything you get from the factory, especially for the price in comparsion too the Hayabusa Pricing. You couldnt build a 1441cc,ported head and cams for the difference in what they cost new. Personally I hate the looks of the ZX14 both gen 1 and gen 2..
The zx14r is really doing better with the heavier riders that need the torque... Down here in Texas racing bikes is like being on a greedy dyno thanks to the insane humidty and temp changes... They zx14r's are not pulling down low 9's stock or high 8's with full boltons... Most are running gen 2 busa times with equal mph... We have a local track pro rider that owns both a gen 2 swb bolton busa and a zx14r swb with boltons... He has run a best of 8.8@158 on the busa and a 9.1@153 on the zx14r.
But!!!! remember this..............................facts are facts!! There are still three 6 second hayabusas and one 6 second cbr1000rr...... The quickest zx14 still runs in the 7.1's... And that bike had Jeremy Teasley on it!!! Just saying!! People act like the new zx14r will change the face of motorcycle racing... all the zx14r is , is a modded up gen1 zx14 which has been out since 2006... many many people have modded them too the hilt...ie crank,ported heads,cams,etc,etc... The new zx14r will not yield 2200cc or make 270whp with full bolt ons... It will do the same thing a gen 1 zx14 will do with the same mods.....the bigger crank,ported head and cams are just done from the factory...
Too answer the orignal questions.. typically a done up 1441 will make 220-240whp depending on fuel and who builted it.....
So stock valves, but HD springs and retainers, along with a mild p&p to clean up the flow...doesn't sound too terribly radical overall 
This was mostly an attempt to get an idea of how the busa would compare to the 14 on an equal displacement level (which I consider to be a more fair comparison of potential; you dont generally compare 4 cylinders to V12's either 
)...seems like the busa is still a very competitive machine on a per cc basis! 
