Do the 1997 small step 42ex with twin 500s benifit from shorties if so how short and what prop .thanks,

Yes it will benefit with -2 shorties. I would only use a 4 blade, like a bravo 1 prop. Some will say to run 5 or 6 blade props, but going with a -2 shorties the props will have a tendency to exit the water more, and the 4 blade will be more forgiving to the drives on reentry.

might be worth a couple MPH ... If you could try a set before you drop 6k & see if its worth the coin , results are all over the map , seems like no 2 boats are exactly the same, IMHO save your $$ & use it for HP upgrades ..those are guaranteed MPH gains