I know that it will make power and it does work, just not convinced it will make the power people expect. How heat soaked are you guys getting? My intercooler stays pretty cold usually. I do not recall the exact readings, but the temps on Armonds intake air temp gauge showed temps that were not that bad. Consider the nitrous will be cooling the intercooler which in turn would be cooling the air and not the air directly.
I will put it another way. The power is not worth the money you would spend on this. Consider the cost of refilling bottles on top of the initial cost. If you would have just sprayed the nitrous into the engine in the first place, you would get the same effects to a far greater degree and make more power to boot. If you want to do it, perhaps you should be looking into a homemade kit using alcohol. It is not as effective, but still effective and much cheaper and you can use something like a windshield washer pump to do it. Just a thought.

05 Mazda RX-8
06 Lotus Elise