My friend Sean's M3 also needed a little love when it comes to the cooling system. Sean wants to pick the car up and take it home. Our plan was to replace the radiator with a Mishimoto Z3M three core unit and a Spal 16" fan. However we ran into a few quirks. We also replaced the thermostat and thermostat housing. We upgraded the water pump to a Stewart high flow unit to improve performance. We also used some new billet radiator stays and a European radiator cover. To cap things off we threw in a Radium Engineering billet expansion tank.