In the cylinders just to get any loose head gasket debris out. As for all the other lil holes, it's hard to cover/stop shit from getting in there. But if any other more advanced Supra owners would chime in they might have a good suggestion for you. I'm a noob when it comes to major repairs like head gaskets... although mine turned out fine for apprx 5 months
till something in the lower end went out.