Originally Posted by Mike Rainbird

First port of call should be a new radiator. No point in doing anything until you have done this. Next think is alloy header tank with high pressure cap (which will raise the boiling point of the coolant - use a 50/50 glycol mix).

Then you can help by sealing the intercooler to the radiator as the air will always take the path of least resistance, so once slowed down through the intercooler a lot of the air will be flowing around the outside of the radiator (if there are gaps for it to do so), rather than passing through.

Finally, get a proper temp gauage as the Ford one is WOEFULLY inaccurate and doesn't give you ANY idea of what water temps you are actually seeing....