overheating w/Nissan motorsports radiator

[Jim Wright]

Water is a better coolant, if you've got too much antifreeze in the
system, your cooling capacity is diminished.  Most antifreeze
containers will have a chart on the back, check that out for the right
levels.  Also, try using Water Wetter from Redline, it'll improve
efficienty of the cooling system.

This is in addition to re-bleeding as some folks have suggested, and
checking the belts, and getting the higher pressure radiator cap too.
;)