you dont have to.... if you have the money... go ahead...you will have to have them installed....from a machine shop... or someone who has tdone them... you will have to have a cam bearing tool
i have the tool... but ive never put them in... dont really know off the top of my head... the machine shop that does all my work puts them in for free when he does my block... or charges me like 15 bucks to just install them without doing any other work