His isn't stock though, he has different pipes and jets in his carb but, you should be getting somewhere close to 100Hp. I think stock it is 96hp but with pipes and different carb set up you can easily get 107hp. That was all I did to my 02 Mastiff same size motor as yours.
Trouble Maker Exhaust
Carb Jets are... .32 .76 I believe.
It is easy to make some horses with the Evo style motors.