tbh i think they are almost entirely useless....

i was running 13psi through one for a few months and on hot days getting acts of up to 60C....normal acts of 40C ish.
i put a charge cooler on instead, and whilst the front was apart i took it to the bodyshop for a little spraying.
basically i couldnt be arsed to plumb all the chargecooler in so i drove it with no water in the system and got the same ACTs

so thats the same act's on a std IC as a heat exchanger with no water