Cam timing changes where in the RPM range the engine breathes most effectively. That being said, when You go to aftermarket parts, You really need to check and sometimes change the cam timing to get the results You want. Retarding the cam timing moves the torque peak higher in the RPM range, at the expense of low end torque. Advancing the cam timing increases low RPM torque at the expense of high RPM torque. The optimum setup varries the cam timing with the RPM. Honda has a device that extends cam duration [holds the valves open longer] as RPM increases on some engines, I am not sure who else may be using similar technology. I don't think I would overly advance cam timing in anticipation of timing chain wear.