Well when you get your valves redone. The can do a 3, 5 or full job. What this does is make the fuel and air mixture flow better into the combustion chamber. The more angles the better. So thats a simple explanation. If your gonna do that you might as well get your intake and exaust ports ported and match them up as well. its one of those more air and more fuel yields more power.

Check out www.jgenginedynamics.com They have 3 stages of head jobs. Between 800 and 1200 bucks. Good stuff. Id rather go with them than gude.