I upgraded from dual 10" to dual 12" SPAL fans on the GT40 but the best part of the upgrade was the digital controller I hooked up. SPAL's website has it. It basically is a programmable controller that turns on 1 fan on at a given temp, then 2 fans at 1/2 speed, then full bore, when needed. It's the best. I am actually thinkling of adding this controller to the Cobra's twin pullers.
