We went over 400 on day 4 in 2012..... and yes, it sucked.
That was a long and loud day with the rain delay and all. At one point on I-40 my passenger reached down to turn up the radio and it was already as high as it would go. Running between the construction barrier and semis at 3800-4000RPM so we wouldn't get run over made for a long day of ignoring the tach and temp gauge lol. Oh yeah and the route sheet was the worst I have had in the three years I have gone.