i advise. I have a 16.6 x44 go devil boat. it is round chines. I have a 31 hp mudbuddy surface drive. how will this boat handle this motor? what should I expect?i had a 27 hp gdlt on it.other than buying anouther boat which right now is out of the question.

It will depend on it your hull is a long transom or short and if your motor is a long or short. If they are both long, good, if they are both short, good, if they don't match, you will probably not get much performance from the setup

long shaft motor, short transom. I took it to gatortrax today and they are going to build up the transom and mount motor on. what kind of speeds should I expect and performance?

No telling bro, all hills are totally different. I would guess around 23-25 empty and 21-23 with a buddy and light load. Should take the turns well with that round chime