In my experience a larger radiator/ one that has more core's, will keep the engine cooler, and with the engine cooler, you get beter performance. I autocross all year long, I have overheated 1 D16 and 2 D15's, so befor I started upgrading my D16Z6 I decided since I work for Flex-a-Lite, and know about the effects of a cooler running engine, I took advantage of the free stuff, adjustable thermostat, dual oil coolers with a 8" fan on each, and dual electric 14" pullers, one mounted behind my radiator and one mounted in front of my exhaust manifold..... I figure the next upgrade will be a decent radiator that will cool beter.

Thanks for the info on all of this, I will PM 2gr84u.