I've had a 16 hp gdlt on a 1436 flat, I just purchased a 1648. Will this thing even plane out or will I need to chit can the motor and upgrade immediately. I know this dead horse has been beaten on here but just curious. I will have just myself and my fishing gear, think I'll see double digits in speed dept?

That's a pretty big boat for that lil motor. Like you said though, the 16 is a tough lil fugger. Put it on there and see what happens. I don't think it will be that much worse than the 14 footer.