I have a similar question , same model boat, but also new to me! Also an Ally owner for over 30! First XTB21. I have a Mariner 200, with a 'Bills' LWP and a Ron Hill (?)OH 14 X 25 prop, with NO CUP!?? Prop shaft is dead even centerline with hull bottom. Hole shot is good, but I blow real bad if I attempt to trim any after plane! Don't know top end yet, since can't lift it up to get there! Look forward to any and all responses!
fatfred69