http://www.racingjunk.com/Parts-Accessories/2494987/7-3-4-quot-Scott-Jet-pump.html

im guessing drag boat jet drive go in a straight line with 2000hp? $4k is pretty steep!

scott pumps are primarily used on those aluminum small block sprint boats that race in dredged out courses. (see below) I dont know much about them (ie what kinda torque or hp it takes to turn them....or how efficient they are compared to the berks/panther/jacuzzi.) I assume they have a ton of thrust, but not much of high end speed as those courses are pretty damn small and tight. with the way they turn, it looks like they are goin insane fast, but they really dont have that much momentum behind them.

i love watching those track like boat races.  those guys have huge balls. 

Thats a scott , they are used in the whitewater river racing.

Whitewater guys typically use Berkeley, Dominator, American Turbine and Aggressors...Not to mention some top secret billet stuff...

These Scott pumps are used in the smaller more agile Sprint Boats...They come out of the hole like a rubber band off your finger...