you cannot use the Pro 2s or any other skunk cam (except the original stage 1, not the pro1) with stock or ITR valvetrain. You need to upgrade valvetrains to handle the increased lift. If you do not, you will have coil bind and your springs with break or not be able to push the valve closed and your valves will "float." Once they do this, your pistons will make contact and a valve will drop. When the valve drops, your pistons bounce the valve head around until the pieces shoot out of your header. your block will crack, pistons will break, head will be screwed, and many other things will be done.

cliff notes for the lazy: DO NOT USE SKUNK 2 PRO SERIES CAMS WITHOUT AFTERMARKET SPRINGS AND RETAINERS!!!