zaleski00

My buddy has a 99 sea-doo gti that it seems like it runs fine when its in the driveway. but when we put it in the water it struggles taking off then it does kind of ok and then when we get to about 35 it starts struggling some more and won't go over 40mph. Now i have ridden this thing in its prime and i know it will do like 55mph with about 500lbs on it and and my buddy and me only weigh like 370lbs together so i know that isn't it. I have taken the back of it off that little black cone and a piece in there was shredded. it looked like a shredded bottle cap but somebody told me that was it. It has not been set up for the summer yet it has been sitting since last summer and my buddy bought it from my uncle and i know there wasn't anything major wrong with it. Any ideas of where to start? and what piece do i need to go back in that cone and how do i put it back on. thanks