Need several pieces of information, like:
* What are you running now? (Engine, heads, cam, carb/intake, exhaust - also transmission, rear axle, power brakes? a/c?)
* How much of an increase are you looking for?
* How does the car get used? (street, highway, race, show, mixture)
* Is it "original" now and how important is it to you to maintain that?
* (Last but not least) Ball park budget?
To give you a "general" answer, an engine is basically just an air pump. Getting more power out involves making it pump more air. There are many different approaches as to how. Give it bigger lungs (more displacement - bore and stroke), make it breathe "more quickly" (cam to make it efficient at higher rpm, [but at the expense of lower rpm efficiency]), make it breathe more efficiently (better heads, better exhaust, better carb/intake), "force feed" air to it (supercharger, turbocharger), or a combination of two or more approaches. That all have their advantages, disadvantages, costs, impact on reliability/drivability, etc.
Last edited by BearGFR; 03-25-2013 at 02:54 PM.