I had a similar problem. My head was warped. The tolerance is .003" in flatness on the head. Mine was out .0035" and overheated all the time. I ground the head flat and everything is cool now. The head may have warped while taking it on and off. Also check the flatness of the block. Putting the block guard in may have pushed a cylinder around a little. Check the block with a straight edge and feeler gauges. I hope this helps. You may also want to try spraying your HG with copper spray. 5 or 6 coats will be fine, and put it on and leave it dry for a day.

 

does it overheat all the time or only when you boost? try to drive the car without boosting and see if you still overheat. if not than i thing i know what your problem is!!

 

overheats all the time just not in boost

 

Bah, you probably dont need a rad unless your roadracing.. if anything get a stocker out of a delsol si