I purpose of the exhaust line cooler is to cool the pressure gases entering the the tank from the pipe. This prevents the fuel in the tank from turning into non-useable vapors, leaving more fuel in liquid form when getting close to empty. This liquid fuel that would evaporate otherwise is what adds a bit more run time. Now, if you run your engines fairly rich, you will not see any benefits. This cooler works only on full hot race tuned motors that are dumping heat and vaporizing fuel (this is the mist you see in low tanks when refuelling) in the tank when the level is low.