i have a 2004 f12 n/a and i am experiencing some kind of grinding noise as if something is stuck in the pump. but i have check several times and there was nothing. ( i know it is normal at idle out of water) but it dose it when i am going full speed and let off the throttle a little bit say going from 60 mph to 35, i am imagining its the impeller hitting the housing, my jet pump bearings are good just repacked them. i dont know is this is a normal noise for the ski but the ski rides and accelerates perfectly, and the noise only dose it when slowing down not on acceleration.