I just bought a new pulley so I am not ready to buy anythin big for about a month or so but I cant stop buying stuff for my truck !! Anyway I was looking at the JDM price list and looked for the cheapest things and what I found was a thrmostat and a breather cap. Im pretty sure I know what a thermostat is for but not a clue on the breather cap. Could someone tell what the advantages are of getting these.