I'll call out or use the bell on the MUP, but I kind of feel that MUPs are for slow sight seeing and cruising with the family. Not gonna call anything out on the roads, if someone was startled by me passing them, they'd be startled be me calling out at them too. The only time I say anything on the road is to cuss out some driver (and usually under my breath because who knows who is driving and what they're carrying). The problem with that is, if I can't vent directly at the driver, I tend to need some outlet because, if I vent about all the crazies on the road when I get home, my wife starts worrying about whether I'm safe out there and if I should be out there. That's why threads like this are so nice.