Even when I deliberately idle down the street to my house, the EGT is higher than I'd like to see it before shutting down. It is, of course, worse when I'm going somewhere where I'm not idling along for a while before shut down (i. e. , getting off the interstate, turning rght into Sam's parking lot).
The big deal, though, is that we tow our racecar 20K miles a year. When I've just finished a long tow, the last thing I really want to do is sit there and wait for the EGTs to drop. As Eric already said, we love our HKS. We use it all the time.
The turbo timers that figure out for you when to turn off would be cool, but with a little practice, you can get pretty good at estimating how long it needs to run to cool down from a given EGT.
mlc (the co-driver)