I also had this recall done. Although I didn't notice any difference in braking performance, I am noticing a new sound that occurs sometimes when start/stop is active. There's a short whirrr sound that happens. It's inconsistent and I'm having trouble finding a pattern, but definitely new since this software flash. Seems most likely to occur when the auxillary cooling fan turns off after running during start/stop being active. It sounds like its coming from a similar area as the coolant gurgle lots of people notice (the sound of coolant being pumped during that auxiliary cooling cycle), but from a slightly different location - sounds near the firewall, though. My only guess right now is it's the sound of the vacuum booster charging, but I'm planning to ask the dealer about it next time I'm in.