just flush out the radiator fluid from the spout on the bottom left corner of your radiator. change out the thermostat. make sure you don't rip the rubber gasket cuz its a dealership only part. put the cap back on the spout of the radiator. pour anti freeze where the radiator cap is. do it slowly cuz you'll see air bubbles come up do that until you see anti freeze come back up and no more air bubbles, then put anti freeze in the container behind your turbo that says special coolant only on it. thats it really. there really isn't anything specific to srt-4's than any other car when flushing out the system