they are volleyballs
Mostly added to keep the boat more level when its stopped and to get the boat on plane faster, They used to use these on the older gamblers before trim tabs were put on them. Made a huge difference in getting the boat on plane faster so you wouldnt go nose up for 30-50 yardsto stop backwash
You can get a little more than a bit. As it settles in you need to tromp on the throttle to outrun the wake or slow down slowly. It can get wet in the drivers seat if your not paying attention.With the big 300 on back, combined with the setback, you can get a bit of backwash.