Hi , iv'e got the arpro p1 and hink it's a good boat for the money and with suitable mods goes very well !. Just puzzled as to how you say it runs a flex shaft as mine has solid 4mm shaft and would recommend anyone to swop that shaft to stainless steel as original is a soft metal and starts to round off easilly at motor end . The setup I've got is standard motor on 3s lipo running octura x443 or x642 props . X642 gives the best drive with no heat issues that I've come across. The leopard 28 series fit straight in with no problems but do remember that high kv motors do pull a lot of amps with large props .yup destroyed my esc the hard way though not finding that the cooling hose had slipped off the rudder might have had a part in it too . Leopard 2845/4420kv worked well on 2s but too fast on 3s for the pond I use !upgrade esc if thinking of upgradeing motor !