Thats really surprising that it hasn't even thought about overheating for you.... Seriously, right before you bought it, every time I would drive it for more than 10 minutes and get into boost, it would try to overheat.
I dunno, maybe the altitude does have a fair amount to do with it. Where I live, in Colorado Springs, we're sitting at a little over 6,000 ft. So it would make sense that it ran better for you, since the car wouldn't have to work as hard. Same thing with your dad's Blazer, I guess, lol.
Regardless, I'm glad its running well for you!