How do I make my 600 fazer faster?????

[nick crisp]

A higher lift but equal duration cam gives engines more low end torque, as a rule it's the duration and overlap that give an engine more top end power.

I can't get my head around why this should be. Can you give a fairly simple explanation for a very simple person?  :rolleyes :lol
Or do I need a degree in Physics/engineering? :book :eek