i have an XX as a few of you know and i have the variable 6- 9 inches, i hear alot of differeant crap to. it depends how extreme you go and how tallented the person is that does the extension. my bike for example has an airtank in the swingarm for an airshifter, and tones of stableizers inside the arm, as well as good welds. i dunno what my arms are rated for proabably around 300. the guy who did it told me 500 HP (though i remain skeptical). Has a nitro busa with around 300 hp, and he claims to have a gixxer 1100 with around 500 hp. so i dunno. personally i will maybe in the future, maybe, shoot for the 300 mark but i will be deffinatly consitering underbraces on it. a company that makes good arms if you want to go buy aftermarket is trac dynamics.
KEEP IN MIND........... when you go off and stretch alot changes, stuff i didnt think about to begin with but became evident dam quick. you will need new brake lines, buy 2 chains, the extensions, a new rear suspension (the stock will not do, i learned the hard way), which also means remove the tail and relocate the plate.
do not go cheep.............. i have seen some real hack jobs for a better choise of words, and by hack jobs i mean a busa with 2 heavy bolts holding on the extensions on the arms. NEVER DO THAT.
i have a buddy with a lightning busa, who had his bike break in half on the highway, so make sure if you get it done by someone they know what they are doing.
hope i was of some help.
