Today was the last straw for my Berkley B cut aluminum impeller. I started the boat up at the river and got out to the channel and started to get on it....but soon after the boat started vibrating as if there were a rock or something lodged in the pump. To make along story short. I'm pushing 650hp and I knew that the Aluminum impeller wasn't going to make it much longer. After taking it apart I found many stress cracks and it's basically junk. My question is what cut of stainless should I replace it with. I have only been able to take the boat to the top end a few times and I hit 81mph but I forgot to check the RPM. I'm thinking of going to an A but if I'm spending that much cash I want it to be the right one. Any suggestions on how to choose? Also what's the difference between the A, A2, A3, and A4?
One more thing I am now concerned about the shaft itself. I have no idea if it is a hardened steel shaft but I don't want that to be next. A friend of mine had one twist on him with 700hp. Are there any markings on them that indicate if they are hardened or not?