I've got a TS 2 with a stock OS .21 XM. I am going to try an Octura X637 prop. What kind of modifications should be done to the prop for top performance with my set-up? If this was a modified motor, what modifications to the same prop would be best? - Jeff.
Once the prop is thinned and ballanced try adjustments in and out and up and down to suit your runing style. I have had great success with the X637 on 21 outboards but do try every prop you can get your hands on as sometimes you will just hit a patricular set up that goes like a rocket. X440 and 440m seem to be the bread and butter props but 215 and 220 Prather and the X438 X640 BC1440 and even an X442 may work well. When you say top performance is it top speed, acceleration out of a corner or just the fastet lap time your looking for? Once you get the trim angle to air the boat without blowing over up and down can change things a lot.