Just took the stang off the road for winter and im taking intake off to do valve cover gaskets. How hard is it to do mabey rocker arms or mabey even lower intake upper intake. What things should i look for how much am i lookin at price wise and any gains hp wise? The cars gonna be off the road till june im basically gonna do mostly suspention work if anyone was any suggestions on things to replace or mabey some easy hp gains i would greatly appreciate them. I have a 90 mustang gt 103k miles on it bassically totally stock.