Suzuki GSX-4 max hp.

I see a lot of tunes for the GSX/4 with 267hp. Why can I only get 250hp?
I'm quite new so forgive me if this is a daft question.

 

Did you give the car an oil change? Doing that increases your power by a fair amount.

 

Thanks Cowboy, just rebuilt engine and changed oil, I now have 263hp! Appreciate your help.