heat spacers worth it?

This topic was covered not even a week ago. The general opinion was that they don't do squat, they're more of a benefit for someone looking for extra clearance between their intake and valve covers. Some folks actually had more problems out of them than anything else.
 
A heat spacer will only make a difference if you have the EGR ports blocked off at the heads and the coolant lines disconnected from the EGR spacer. Otherwise its a waste of money unless you need it for clearance.