Thanks Jim! I will spend some quality time with that site.

So, then, do modifications such as larger valves (intake and exhaust) and port work alter the volumetric efficiency? I'm thinking that if the engine has larger valves, it would be able to suck more a/f in and push more exhaust out. Of course, if it's more about the engine's ability to draw air in, then larger valves would possibly flow less due to a lower velocity. Just trying to wrap my head around it, ya know?