I've never used a heat sink but do use a cooler on my 727s. I have the deep pans on my cars and run the temp gauge sensor in the front right side of the pan. With the tub and fin style cooler I would see temps north of 220 degree when going rounds. I have since switched to plate style coolers and haven't seen temps above 190. I have a CSR shield on the one car and it does warm up a little quicker than the car without, but still doesn't go north of 190. The coolers with fans are great if your street driving, but with a drag car that you try to cool in between rounds only the fluid in the cooler is being cooled when the car isn't running. I know some of the fancy ones have thermostats that turn the fan on automatically. I'm a little particular with trying to do the same every run so last thing I'd want is for the fan on the cooler to turn on mid run and possibly change the E.T. ever so slightly.