I get really over-heated while racing (me that is, not my car), I've been putting off purchasing a cool vest for a long time. The technology in the cool packs has really improved and wondered if anyone had good experience with a particular product? Im not taliking about the cold water pumping system but the vest you wear that either maintains a temperature or you freeze then put it on. Im concerned with the freeze type, it will do just that, freeze (my chest and back) for the first 10 minutes then melt and be useless. Any thoughts or suggestions would be appreciated.