ie..force induction - turbo chraging/supercharging or normally aspirated - cam profile/stroking (computer chip/high flow exaust)...depending on your budget
It will really depend on the type of engine and how much power you want.
how can i hack a honda engine
It depends on which Honda engine your talking about. An easy trick on some models is to remove the intake silencer to free up power. Aside from that you can keep the internals clean for more hp, use a synthetic oil, and insulate the intake from under hood heat.