Why don't more boats run these? they are about half the cost as the Jabsco or Merc replacements. Do they not move as much water as the OEM?

I am considering changing mine from the Merc pully driven pumps to these crankshaft mounted pump since i need to replace them anyway this winter. I have pleanty of room infront of the motor an it would be easy to run the plumbing. Would there be any reason not to use these?

Volvo Penta 496s use these. They are easier to replace impellors, no belt or adjustment to worry about and flow plenty of water.

My friends Volvo/Penta also runs one of these. It's easier to change impellers.

Ditto, have one stock on SBC Volvo and I love it.

One more vote for them. I have a set on Marine Power 502s. Move plenty of water and easy to replace impellers.