Kinda both.Between the time the valves open due to the height/size,and also width depending on the cam(s) choice is where you will increase both power,and torque,which will also move your power,and torque curves in the rpm.But other parts play a big factor to to help the cams get their gains,aswell work properly.Heads,intake,valve size,ects.These things will play a big contribution on how those cams will work.