There is a lot of heat it seems under my hood now, its making the rubber seal on my intake brittle....before I go to where its 121 degrees, Id like to do a bit of preventative maintenance ........ or find a vent for the hood....either or
Considering Nissan has there proving grounds in Arizona. The stock cooling system works just fine even in this miserable heat. Doing an upgrade on such a new vehicle would probably make something else worse and now you have problems that could have been prevented by simply leaving things alone.
i would get some tech line coatings 2,000 ceramic paint for your exhaust manifold.... and i would also do some ceramic window film on your back windows and llumar winshield film... you can get the whole package of special tint at tintzoom.com then have a local mobile installer come out and install it.
I just noticed that your X is an '11. That is after the "SMOD years," so there is no compelling reason to change anything in your cooling system.
If, after you move to Arizona, you experience cooling issues, that would be the time to address the situation. In the meantime, change the coolant at recommended intervals with the proper coolant and just enjoy your X.
Given they run Xterra's in the middle east with out issues you shouldn't need a radiator upgrade for Arizona. If you're having heating issues where you live now then you might want to consider that there is something wrong and get that checked before replacing the rad.
have you tried/considered using Redline's Water Wetter?
I use that here in the heat of wichita falls in all my vehicles and keeps things cool. I especially notice it on my motorcycle as it has a digital water temp display. typically 15-20 degrees cooler with the water wetter/distilled water mixture. (no coolant at all)
I suspect the thermostat wouldn't care how large the radiator is or what additives are in the coolant. You will probably still see 190-205 degrees on the coolant temp, which is within the operating range. The factory cooling system is very capable of doing the job. If you feel the need to replace, the Koyo part that Robert mentioned above is a direct replacement, no modifications needed. I know of one Koyo that replaced a factory radiator earlier this year, and it has undergone rigorous testing and monitoring all summer in the southwest (including AZ). I have only received positive feedback about it.