I got an 8x4 prop for my 9hp lt and i cant get any rpms. Now i dont run mud and the prop has a heavy cup, question is if i remove the cup will this act as pitch removal or should i just work the diameter down or both to gain rpms?

thats the sandard size prop for a 9 hp so u might have oher problems like dirty carb or govonor out of adjustment or throttle cable stretched!!!!!

The 9hp briggs Vanguard we are building now is going to have a 7.5x4......

just built it. motor has 2 hours on it. on my 16hp i ran a backwater 9x6 and a gd 9x3 and they ran at about same rpm. the 9x3 has more cup. i dont know the maker of this prop but it is heavy made and more cup than my 9X3. does cup in a way = pitch? if i remove it how will it effect its performance?

yes the cup on a prop stops the slip!!!! cup is like a tire with alot of rubber left vs. a bald tire!!!

Removing cup from a LT prop can have bad results. The cup on gdlt keeps the prop n the water. As the cup wears off the prop will come out of the water when running open water.