Im giving realistic numbers myself, because we have STI's that dont even have 500hp and they are running 10's. Im saying based on MY experience that he can run 10.5 or less any day with that kind of hp. Just depends on your driving skills and the rubber, period.
If you dont believe me, check on youtube "bonsai sti" and it made 10.93 at 129mph and its running a FP Red with a Spearco tmic and nitto drag's.
I dont know whats YOUR experience on cars but it doesnt look productive.