In actual fact you don't realy need to cool them down after a fwy run, cos the car runs alot cooler with all that fresh air passing through it. Driving in the city, whether it is at 40,60,70 k's will actually make the car hotter cos there is always someone in front stiffling (sp?) your air supply. And the turbos are not water cooled, they are oil cooled, meaning that when you turn her off after a spirited run the oil left in the turbo will start to glaze the insides of your housing causing premature wear. A turbo timer is not needed if you can be bothered sitting in your car for upto 30secs after the drive. If you have been giving it WOT for some time then a couple of minutes is advisable. Turbo timers are deemed a necessity only by those who sell the bloody things! And yes I currently drive a turbocharged car with out one fitted and have done so for the last 5 years, and the turbo is fine.( can't say the same for the diff though )