The 125hp version wil already make you a poor man..
Im not sure but i think it wil be something in the region of 8000$
Camshafts
Bigger valves
headwork (porting ect)
Connecting rods
Bigbore cillinders
forged pistons
balancing
Oilpump modification
Powercommander or equivilant
Exhaust system?
manual labour inc usage of the workshop equipment (mill, lathe ect)
ect ect
It could even be more than 8000$
Its personal, but for me its not worth it.......i rather spend it on the chassis,wheels,forks,brakes,shock ect