hey i am looking at the SkunK2 web sight for head gear; for my GSR motor. and in the collum of the cam shaft that i want to get it says, "valvetrain upgrade recomended" does this mean i shuld also replace valve springs, valves, retaniers, Intake manifold, and cam gears? do i have to replace all of these?? and i know skunk2 is a good brand for headgear, what are some others, i mean i dont know if i will have $900 for just camshafts. any help will be appreciated