as suggested in rat's post get yourself some lightweight wheels... you'll be amazed at the difference they make.
granted the engine upgrades are cheaper individually but even when added all together they still won't make as much an overall impact as putting a set of lightweight wheels on. you'll reduce the effort of your suspension while improving braking, acceleration, and steering.
and i bet you'll be able to find a set of wheels a lot easier for a newer model...
interesting the stuff on duc.org's project monster page. i wish i took as much time to weigh all the stuff i yanked off my s4 along with all the stuff i added. most significant bits noted here: http://www.ducatipipemod.com/s4/weight.html
forgot to account for removal of:
rear seat cover
cut portion of frame
bunch o' bolts
some "unessential" wiring
stock exhaust (d'uh!)
stock CF fenders
sprocket & clutch covers
stock bar risers
stock brembo M/C's
crank-case overflow bottle
never weighed following installed parts:
bar-end signals/rear flushmounts
new cf fenders
some TI and ergal bolts
c'cat clutch & sprocket covers
having an accurate scale at home would've helped i guess. trucking this stuff all to the post office got a bit tedious after a while!
Im a big fan of weight reduction (bike's not my own )
more power is all well and good, but less weight yields benefits in acceleration, braking and handling.
here's what you can do with a big budget: http://www.monsterhooligans.com/member_profiles/profile_jn.html (james is in the process of dropping in a hopped-up 900 motor, so he is going to have power too...i hate him)
I would stick with the biggest weight dropping items
wheels, tank (CF or Al), pipes
I think weight reduction would be the way to go instead of heavy engine mods. You could keep your easy to live with reliable motor plus if you ever decided to sell or trade you could keep alot of your lightweight parts to use on you next bike.
My Gp Due weights 310lbs. While it is a track only bike and therefore has no lights I still run a starter. In the beginning weight reduction is pretty easy and relatively cheap as you go it gets more expensive and in ever smaller bits. Power increases work the same way. I haven't experienced anything negative about a lighter bike except maybe some items wear out faster like aluminum rear sprockets. You have to judge the value of that. On the track the lighter the bike the better. Race bikes would all be lighter then they are now if it weren't for the rules. In every professional series there are minimum weight limits. There two reasons for the minimums the lighter they are the faster they go and they get much more expensive so in an effort to even the playing field they limit the weights. Check out my website for more pictures. http://mywebpages.comcast.net/aortner264789mi/FirstPage/GPDUE.htm