Dead on, the bearings also need to “seasoned”. This is the mating of ball bearing with riding surface. High stress too soon will compromise the bearings. I have seen many differential builds go back due to overuse prior to seasoning of the bearings. We paid a lot for these cars, give them a fighting chance.Remind your service manager that the transmission and differential are also part of the drive train and have new gears that should be given at least a few hundred miles to smooth in together. I have known of a few people with performance cars with the same mind set of just get in it and let her rip because as stated most modern engines can handle that but later complaining of whining from the rear end and don't know why, because they didn't just give those gears a little while to mesh in smooth together. Duh!!