You could lighten up all the internals so it will spin faster, then lighten up the vehicle. Making the vehicle lighter pretty much equates to adding H.P. at the bottom line.
Ah but he didn't ask for how to get it faster/quicker...lol.
If you want it to feel faster with a little time and a few bucks - a shift kit, a good ignition re-curving, and some decent rear gears will get it a goodly way towards quicker.