if your getting 32mph with a 17 pitch at 6000rpm then something is very bad on your set up. the speed should be a lot more or the revs less.i think you need to find out exactly what revs your getting, and the prop might say 17 but infact be a lot smaller !!!what diameter is the prop ? the 13x19 at 6000rpm would put you in around 38 to 40mp with 10% slip. to be at 32mph you must have at least 28% slip, that would be realy realy bad. Need to know exactly what this prop is and exactly what the revs are, you need a real tacho and not just think its 6 thousand rpm.. phill