Being in Vegas I have similar climate. The best cooling mod IMO is an electric Meziere. Think about it, when do you put the most strain on your system? Sitting in traffic with the AC on and no air moving over the radiator. It is at this time that the pump is pumping the least amount of coolant through the system when you need it the most. An electric pump runs full bore all of the time pumping the max flow when you need it the most.
My gauge used to sit right in the middle. Since installing the Meziere it has never reached that same point on the gauge. It stays one notch cooler than it used to all of the time. I have actually seen my gauge go down idling in the staging lanes after a run.
Added little benefit is if you have aver snapped a belt, you can still make it a ways without worrying about overheating.