Another thing that is good is a good water pump. those cheap crap ones with stamped steel impellers are not very good and allow a lot of bleed by. I used a water pump made for marine purposes and has a brass impeller with a back plate on it. it provide more water volume and last a lot longer with stainless steel shaft and better sealed bearing made for harsh marine environments. I bought mine here on Amazon
http://www.amazon.com/MERCRUISER-WATER-CIRCULATING-GLM-Number/dp/B004AQUABY
