With stock Raker ,propshaft should be around 2-3 inches below bottom of pad for starters. Need to get in the 5500-5800 RPM range. Should put you in 65-70MPH area depending on setup and how big yer boys are


. Need to pin the carrier on that unit if you run a surfacing prop, and that unit only has a lifespan of about 100hrs as the housings warp. Also drill out the passage from tab back into case as some where to small and didn't supply enough water to cool prop hub which melted hubs out.