i have one. i never took off the clutch
but i got alot more speed out of it buy changing the prop angle and dept.
that helps the nose stay down , but it depends alot on water currents and wind. one way you go with the wind and current and fly flat and fast, turn around and you have to be careful holding it wide open.
the stock prop cannot be moved soo either change out the parts or just put nylon washers between the prop arm and hull.
also slotting the holes for the turn fin so it can be ajusted to be parrallel to the side of the boat ( perpendicular to the water ) will help speed but cost
i had problems with mine out of the box but fixed them since
-gas tank leak ... two tanks in a row
-flex shaft stripped at the clutch bell due to poor alignment after first 1 min
-header pipe wrong angle to match exhaust perfect went flex shaft properly aligned.
i don't know i they are all like that but just be sure your flex shaft is able to slide in and out of the clutch bell before using, also check your muffler slides onto the two o-rings for propper flow and speed.
as for speed ... i've been using it for three years now , and i still need to go for a piss real bad before using it ( no matter if i just went or not ) and my knees shake the hole time i'm driving!