mine had a notched transom but has been filled. one advantage to 25" is the motor will lift out of the water 100% with a 25" and will leave the bottom of the lower unit in the water with a 20". In really rough water the 20" will allow water to enter the splash well more so than a 25" but really shouldn't matter because the well drains anyway. One big thing is larger HP V6 motors are now more avail. in 25" shaft. It's harder to find a 20" high HP motor now. Most brand new bass boats now even have a 25" motor on a jack plate. back years ago a long shaft was an odd 22.5" motor. short shafts then were 15" and the average was 20". Now you have the 15",20",22.5",25",30",and some 35" now. So now the average is 25" but heading to the 30's real fast.