these do work. are there certain days when they will work better than other days, yes. everything in those links posted is subjective and those peoples opinions because they think they know how the fuel tanks are affected by the exhaust pressure. have they run them, doubtful. common sense will tell you this...your engine runs around 230 degrees, how hot do you think the exhaust it? hotter than hell! any little bit you can do to cool the gas will help. a cooler fuel/air mixture will produce more power, thats why drag racers pack ice around the air intake on their cars. put a cooler on your car, run it for a qualifier, and grab that cooler when your done running, they are hot! now tell me that means it doesnt work. its doing its job by absorbing heat from the air.