Ok I am likely overthinking this as usual. Feel free to say so. But Our new to us Onyx Xt i rated at 260Hp and I am sure that is at considerable boost pressure and related charge temps. I tow a 1600LB Scamp trailer and can maintain any speed (65) i feel safe. But In the event I travel to the higher mountains with long lengths at 6+ % grades I would typically reduce my speed to ease the load and heat generated. Is this counter productive on the OB or even the Ascent. The only cooling air passing thru the intercooler comes from forward motion and no fan to assist it. Plenty of cool air at 70 but what about at 45. Or extremes at 30 mph. Some of the grades are many miles long. Where does the slow speed become worse than higher speeds and more power needed. Is there a fan kit designed to assist the intercooler. Water spray nozzles seems to be excessive but Is IT?? I did a radiator water spray system on my 1987 26 foot motorhome to better handle the Colorado I-70 interstate in high summer temps. and the 117 deg in Utah and Nevada It ran from the 40 gal of Fresh water in the motorhome It did make a difference in extreme conditions. One could even power it from the boost pressure with a tiny1/8th 3/16th line plumbed into a small reservoir of distilled water??